Saturday, November 21, 2009

A new field guide for trees

Wintery view from my trail up Mt. Sentinel a week ago.

After a few rain and storms came through our area in the past few weeks all of our plants have pretty much finished their season. As I mentioned last month an early freeze led to many of our trees having their leaves killed before they were hardened off, so we still have most of our ornamentals, such as Norway maple and European mountain ash with most of their leaves still on the trees. But Montana natives are pretty much ready for winter. So am I, all we need is some snow!

Two weeks ago I was able to visit coastal Alaska, near Ketchikan along the coast. Winter has definitely arrived there, but interestingly they have had a relatively mild November (it was warmer than Montana). All the leaves were gone from the trees except for a few willows and alders that were protected from winds and rain. Lots of adventure traveling there this time of year, you never know if your plane will make it on time with all those storms, fog and rain. Ironically my biggest problem was getting back to Montana with fog covering the airport there…

This month I thought it would be useful to mention some new books coming out that should be interest to all of you
doing phenology observations, and also just for general interest in learning more about the natural history of our trees and plants. A few weeks ago I got a review copy of the new “Sibley Guide to Trees”, published by Alfred A. Knopf, and available in most bookstores. This is Sibley’s first entry into the tree field guide area. David Sibley is legendary among bird watchers for the beautifully detailed illustrations and overall usefulness of his bird guides. His books in fact set a new standard in field guides when they first came out.

This is a pretty ambitious field guide since it covers nearly all native tree species to North America, and also most common cultivated trees and even some shrubs. So for budburst this is a great reference to most of the trees people make observations on, and since it covers so many species this makes it easy to tell if what you are observing is actually the native species or some closely related ornamental, for example. The other thing that is really useful here is that this book also works hard to cover all the flowering and fruiting stages of most groups of trees. This is something that is often lacking in other tree guides, and particularly useful for people making phenology observations. Also it includes illustrations of the variation in shapes and sizes of leaves so you can easily get an idea of how each species varies (something that drives people crazy – leaf shape and size can be so variable!). This is not a technical guide, so if you are interested in getting into all the details and having more definitive information on identification this is not the right guide for you.

For a more technical guide to trees of North America you can consult for example John Farrar’s “Trees of the Northern United States and Canada”. This is more of a desktop reference, but includes lots of photos, more descriptive information, and technical keys, when necessary. This does not help much if you are in the southern part of the country, but for northern areas this is a good one to have. I also recommend Allen J. Coombes book “Trees” which is the in the Smithsonian Handbooks series. This book offers simple keys and clear beautiful color photos of all of the species covered. In this book the focus is on commonly cultivated trees in temperate areas. This is a great supplement to Sibley’s book when you are looking at street trees or trees in parks that may be exotic species (which at times can be easily confused with native species. For winter tree ID I still find George Petrides books in the Peterson Field Guide series on the of the best, since you get nice silhouettes of each type of tree as well as good information on bud and twig ID which will be pretty handy until the leaves come out next spring!

Western serviceberry twig

Thursday, October 29, 2009

Early Frost Shows Effects of Extreme Weather Events

Sudden hard frost turned all the leaves of these shrubs brown and
“freeze dried” them to branches, so that leaves will drop weeks
late this year. Mt Sentinel, near Missoula, MT.

This has not been a great year for fall colors in many parts of the country. In some places like Minnesota nice fall colors were cut short by an early intense frost. In much of the Rocky Mountain region an epic frost hit in early October before most species had even begun to come into color. All of this points out how sensitive plants can be to changes in the timing of seasons, and how much you can learn by keeping careful records of phenological changes as we do in Project Budburst. When we think of frost damage we usually think of early frosts in spring and how they can have devastating effects on fruit trees for example. It is generally true that plants are particularly sensitive to frost when tender new leaves and shoots have just formed. But unusual fall frosts can have damaging effects too. Some data suggests that plants can become more sensitive to frost damage with climate change, just because they are not as well prepared (not hardened off) for these temperatures when mild or shorter winters prevail.

How trees prepare for winter varies by species, and for ornamentals where they were bred. What generally happens is the process starts when night length exceeds 12 hours, or after the fall equinox. As cool temperatures, normally in the 40 degree range occur at night this can hastens the process of hardening, where plants change their chemistry, in particular the balance between starches and soluble sugars making them capable of withstanding progressively colder and colder temperatures without tissue damage. They continue to harden off from the beginning of fall all the way into the dead of winter, when some trees can tolerate temperatures of -30 F or more without visible damage. The ability of trees to tolerate these extreme temperatures in fact explains the northern distribution of many tree species and also why conifers dominate the northern or highest elevation forest regions (they can withdraw more water from outer areas of trunk than hardwoods, preventing damage from ice crystals).

So while here in Montana temperatures of 5 or 10 degrees are something that all our plants should be tolerant of in the dead of winter, when these temperatures occur all of the sudden, and in early October they can cause a lot of damage! The 30 year normal first hard frost is in late October or early November, but we had our first frost, which was a hard frost (28 degrees or colder) on October 6th. We had hard frosts every day over a week, including the worst frost on Oct 13th at 3°! Three more days with temperatures below 10° continued to hit our plants over the past two weeks.

In our area the main effects of several days of early severe frost were easiest to see on ornamental plants that appeared to be the least hardened off when the Arctic Front hit us. Leaves went from lush green to gray, brown or black within a day or two, and many also had leaves that curled up, but still held firmly onto their twigs and branches.

Interestingly in our local paper the City of Missoula announced that their leaf pickup dates for street cleaning were delayed until further notice. Another great example of how we try to plan so many things way ahead of time for efficiency, but sometimes mother nature throws us for a loop.

So why are are the leaves not falling when they normally should in the fall? As I mentioned in the budburst blog a few weeks ago most plants use day length to determine when to start hardening off, and when to start cutting off the flow of water to leaves, and the flow of sugars from leaves to the stem. Cool temperatures (but not freezing) can accelerate this process as well. The timing of leaf colors is more consistent in terms of a calendar date than the timing of spring flowers. So if a severe frost occurs before the leaves have begun to turn colors then it is likely that they have not completed growing an “abscission layer” or a corky growth that cuts of the flow of liquids between the base of the leaf and the stem. So in essence the leaves were “freeze dried” to the stems. Now it has been several weeks since this series of killing frosts so with this warmer weather some leaves have hints of yellow or orange from the small remaining sugars that still occurred in the leaves, and have begun to finish developing an abscission layer.

A few individual paper birches, and silver maples turned colors before the frost, and they are losing their leaves close to the normal calendar date. Western larch a conifer that is deciduous is also turning colors close to its normal date, presumably because it was more hardened off when the frost occurred. But for most of our native budburst species, we now have stiff brown leaves. They will come off when we get our first hard rain or windstorm. For many of our plants in Missoula this occurred last Friday (Oct 23rd). Look for the effects of these weather events on the plants in your area, it often makes a difference in determining when your plants get to the 50% leaf fall stage. For many of us up here in Montana the Budburst Phenology season of 2009 is virtually over. It will be interesting to see how the season unfolds in more southerly places now.

In the meantime now is a good time to enter the last of your budburst observations for 2009. We are anxious to start analyzing all your data from this year. Now with three years of budburst data for many places we should have enough data to begin to see some trends. Stay tuned for further news on our results…

Paul Alaback

Photo Captions

Photo 2. When the first heavy frost first hit on Oct 6th, a light snow occurred as well. Only the most northerly of ornamental trees were in color. Here we see sugar maple and paper birch giving the only color we saw this fall.

Photo 3. Black locust an east coast and Midwest native that is commonly planted as an ornamental in the Rocky Mountain region is one of the last trees to turn color and shed its leaves in the fall. This year most leaves turned an odd gray color, with leaves curling up in response to the severe cold. Few of them have yet lost leaves from their branches.

Photo 4. Common snowberry, usually has yellow leaves that turn in early September and persist for a month or more into the fall season. This year many have turned brown or even close to black where the frost was particularly severe and long-lasting. Notice that the leaf here that was starting to turn yellow in the center, but then had frost kill the margins of the leaf.

Thursday, October 1, 2009

Fall comes abruptly to northern states

Much of the northern plains and adjacent Rocky Mountains got a good frost this morning, so Fall has arrived rather abruptly with this big storm system. For weeks now we have had these amazing sunny days and unseasonably warm temperatures over 80 degrees. Half dozen forest fires were sending smoke all over the valleys around Missoula just a few days ago. Now it is clear and cold again. The silver maple (Acer saccharinum) in my yard has about 40% of its branches covered with crimson leaves, so maybe in another day or two it will reach “peak color” phenophase with 50% or more of its branches with colored leaves. Ashes (Fraxinus spp). in general and green ashes (Fraxinus pennsylvanica) in particular are already in full color around town as well as red maples (Acer rubrum) and American lindens (Tilia americana), not to mention the “burning bush”, or Euonymus alata. The later is an ornamental from Europe which has spectacular bright red leaves right now (giving it its name). Here in the Rockies it is well behaved and stays in peoples’ yards, but in the Midwest and east it can be quite invasive and problematical.

For those of you that have recently started budburst now is a great time to start making observations – you don’t have to wait until spring. There is a lot to learn and appreciate by looking at fall color patterns of both native and ornamental plants!

While some parts of the country celebrate fall colors in a big way, such as New England, the

Midwest, and much of the eastern deciduous forest region, any place that can get cool night temperatures (but not freezing), and warm days with deciduous trees and shrubs has a good chance of producing beautiful fall colors. On the Pacific coast, for example, colors are often muted due to mild temperatures, but at high elevations they can still get brilliant colors from huckleberries, cottonwoods, larches and aspens. Here in the Rockies aspen and huckleberries have been in full color at high elevations for weeks already. Reports from northern Wisconsin and Minnesota suggest many full colors there already. Most parts of the country should be reaching peak colors in the next couple of weeks.

Patterns in the fall are quite fascinating. You can really see the influence of both genetics and environment and how they interact at this time of year. For plants timing of phenological events is critical to their survival and their ability to compete with other species. Plants need to be able to shut down their leaf pigments (chlorophyll) and harden up for winter (tolerate freezing) at the “right time” which is a balance between the opportunity to capture energy from the sun and store this energy as sugars and starches as long as possible, leading to greater growth and health vs. the increasing risk of damage from frost. Plants determine the time to change colors by responding to changes in the length of the day. So you can tell where a plant comes from (or where it evolved or was bred in a nursery) just by looking at when its leaves turn color in the fall. Plants from cold northern climates, such as American linden and red maple often turn color first. Plants from more southerly locales such as the common apple (from around Turkey) and the apricot (from Armenia) often are the last to turn color in the fall. So they have a higher risk of frost damage, a fact well known to people in the fruit industry up here!

Even within a species you can see differences in genetics by looking at fall colors. On a given street or park you can often see many individual trees of the same species, say Norway maple (Acer platanoides), paper birch (Betula papyrifera and B. pendula), or around here the ubiquitous honey locust (Gleditsia triacanthos). But some trees may be in full color while a nearby individual is still green. If the trees are side by side presumably they are experiencing the same weather conditions, so there must be a difference in genetics (or where the parents came from). Weather can still affect the speed of color change and the intensities of color. You can see colors develop first in open areas where it is colder at night, and develop last in protected shaded areas where it is warmest at night (the shade from branches holds the daily heat more effectively).

There are several species that are

still flowering, and some are just now starting to have ripe fruit such as green ash (pictured), lilac, sagebrush, and boxelder. There is a lot to see and enjoy out there right now before the grip of winter ends another phenology season.

Paul Alaback


1. Huckleberries (Vaccinium globulare) in full color (and tasty fruit) at 7200' near Bowman Lake in Glacier National Park, last Thursday.

2. Common snowberry (Symphoricarpos alba) in full color at 4300' elevation on Mt. Sentinel open space trail near Missoula, Montana last Sunday.

3. Rocky Mountain maple (Acer glabrum) in full color on rocky gully at 3500' elevation near Missoula, Mt. last Sunday.

4. Fruits beginning to ripen on a green ash (Fraxinus pennsylvanica) in Missoula (elev 3200') on Tuesday. Note these are called "samaras", very similar to maple fruits. When they ripen they turn brown, dry out then quickly disperse in the wind.

Thursday, July 16, 2009

The "Green Lull"

Thomas Jefferson used to refer to the progression of blooms in his garden as acts in a play. Tulips were an early act; lilies were a later act. If we extend Jefferson’s analogy, the prairie must be in intermission right now. This period is sometimes called the “green lull,” the time when spring blooming plants have finished and the fall goldenrods, asters, compass plants and other beauties, haven’t opened yet. Having just driven home from St. Louis to Chicago two days ago, I might amend “green lull” to “green and dull.” There just wasn’t much to look at!

Admittedly my botanical skills are challenged at 70 miles per hour, but I did recognize a few glimpses of color as I drove along. Native species were few and far between, but I did see bee balm (Monarda fistulosa), purple coneflower (Echinacea purpurea) and common milkweed (Asclepias syriaca) in full bloom. It was also nice to see many plantings of the native whorled milkweed (Asclepias verticillata) blooming along steep banks of overpasses. It is a substitute for another erosion control plant, crown vetch (Coronilla varia) which has widely escaped and is considered invasive. Other invasive species seen blooming along the route were teasel (Dipsacus spp.) and the first purple spikes of that wetland scourge, purple loosestrife (Lythrum salicaria). Although it’s tempting to put a hardy plant in your garden that defies the green lull with its showy purple blooms, please don’t do it. Purple loosestrife is invasive across the US (worst in the Midwest and northeast) and can take over a wetland in a blink of an eye. Cultivars reported to be sterile are not; they will easily cross with other cultivars or the wild type of the species. Purple coneflower, blazing star and lobelia will also give you color this time of year and are great substitutes that will not harm the environment.

Tuesday, June 9, 2009

June 9th. Cool weather on both coasts leads to great floral displays this month

This past few weeks I had the opportunity to look at the phenology of plants in both the northern Atlantic and Pacific coastal regions. Both regions have had somewhat cooler than normal springs, with parts of the northeast being quite dry, but recent rains are quickly compensating for this in both areas. On Washington’s Olympic Peninsula last week I actually saw plants in the rainforest wilting from the extraordinary heat and dry conditions there! This followed with heavy rains over the past few days. Even here in Montana we have had cool rainy weather to start out the Month of June which is usually our wettest month.

We have written here before that temperature is a key factor which generally determines when most plants start growing in the spring. When we have a cool spring as many places have seen this year, plants generally come out later. Here in Montana for example while a series of warm springs over the past 10 years or so has led to flowers coming out as much as 2-3 weeks earlier than in the past, this year plants are coming out right at about the average date (the first time flowering dates have been “normal” in nearly a decade). The other good thing about this cool wet weather for gardeners, and also for those that appreciate spring wildflowers is that this also tends to extend the flowering season. We have seen flowering periods extended a week or more for serviceberry and many garden bulbs this spring here in the northern Rockies, while chokecherry was flowering during a warm period recently, so it only lasted a few weeks.

In New York if your travels allow you to visit the New York Botanical Gardens in the Bronx, now is a great time to check out early summer wildflowers and the last of the spring wildflowers. When I was there over Memorial Day weekend Rhododendrons were in full bloom all over the gardens, and azaleas were in full bloom as well on the margins of their amazing old growth forest reserve. Tulip poplars were in full bloom too, although flowers were beginning to fade on some trees. Most pines including eastern white pine were at the first needles stage. Woodland wildflowers such as blackberries, solomon’s seal, viburnum, and mountain laurel were beginning to show. Native flowering dogwoods are done flowering, but the ornamental Cornus kousa, from China and Japan was beginning to reach full bloom in the main garden areas.

In Washington’s Olympic Peninsula by contrast Rhododendrons just recently came into full bloom. In Washington Rhododendrons grow so well they are sometimes considered weeds. I saw some shrubs 10’ or more high there, all covered with red or purple blooms! Spring wildflowers such as trillium are still in bloom there, and the raspberry relative which is native to the coast, salmonberry (Rubus spectabilis), is just beginning to flower. Volunteers in Alaska report that further up the coast spring and summer are quite late this year as well. Spring is just starting up there.

The same varieties of Rhododendron just came into bloom last week here in Montana, at least two weeks behind those in New York. A common ornamental dogwood here, called the pagota dogwood (Cornus alternifolia) is actually native to woodlands in New York.

But because of the cooler weather here it is still in full bloom weeks after it was done flowering in its native range (at least in the Bronx). All of this points to value of making budburst observations not only of native plants where we get the most useful information on the ecological effects of climate change but also your garden plants since varieties of perennials or trees and shrubs are genetically similar, so any differences you see in flow ering dates around the country should directly reflect climatic differences. Make sure you note which varieties you have when you register these plants! (enter in the notes field).

Modern interest in phenology and citizen science actually comes from the observation that most homeowners or residents of dry cold northern areas, such as Montana are quite aware, and usually keep track of when lilacs first come into bloom into spring. Finally some color to contrast with the brown of a long winter! By just organizing volunteers to keep track of the day of first flowers of these shrubs has resulted in an invaluable dataset for looking at how weather affects plant phenology (for more information on the history of this see

A good example of looking at effects of weather on regional patterns of phenology comes from red maple. Native to the eastern US, but widely planted as an ornamental across the country it can be used to show how plant phenology varies as you move across the country. According to budburst observations from volunteers this year it started flowering in Houston, Texas on January 23rd. Nearly a month later it started flowering in Arkansas on Feb 15th. In New England it started flowering in by the second week of March to early April. In Montana it was flowering even later, in mid-April. If you live in the Midwest or west and have a red maple or black locust planted near you please keep track of when it flowers next year. It will be interesting to see what pattern it has across the diverse range of climates in the West.

Paul Alaback

1. Azalias and rhododendrons at New York Botanical Garden during early June
2. Flowering dogwood in early spring at edge of old growth forest preserve at edge of botanical garden
3. Tulip poplar blooms during full bloom over Memorial Day weekend
4. White pines at first needle phenophase in New York
5. First flower phenophase for red maple in Montana

Monday, June 1, 2009

Summer Begins to Show around the National Mall with the Flowering of Native Species

(Guest entry by Mary Byrne, Botanist and National Coordinator of Seeds of Success)

In early April the annual Cherry Blossoms Festival in Washington, DC attracts thousands of visitors from around the world to the National Mall. This is truly an amazing event – thousands of people in one place to witness the peak bloom of a single species! However, this phenological event lasts only a few days, and by late May the delicate cherry blossoms are the far from the main attraction in the nation’s capitol. But what botanical beauty can be found on the National Mall to delight the next wave of visitors that flood the Capitol over Memorial Day weekend? This past weekend, I decided to talk a stroll around the Mall to find out what native species are ringing in the beginning of summer.

My first stop was the U.S. Botanic Garden at the base of the Capitol. The USBG recently renovated the three acres on the west side of the Conservatory, now known as the National Garden, which features species mostly native to the Mid-Atlantic region. Before reaching the National Garden I was stopped by the oak-leafed hydrangeas (Hydrangea quercifolia ‘Alice’) almost in full bloom at the front entrance. From the entrance into the National Garden I passed under an arbor covered in the purple and white inflorescence of American wisteria (Wistera frutescens) hedged with the feather like creamy flowers of Virginia sweetspire (Itea virginica ‘Sprich’). Once in the full-sun of the Garden a myriad of other species were in peak bloom; snakelily (Dichelostemma ‘Pink Diamond’), evening primrose (Oenothera lindheirmeri), Small’s beardtounge (Penstemon smallii), lyreleaf sage (Salvia lyrata), and foxglove (Penstemon digitalis). I wasn’t the only visitor enjoying these flowers, the pollinators were busily buzzing among the garden too!

The path through the Garden leads one to a view of National Museum of the American Indian, just across the street. The Museum is surrounded by a garden, representing over 145 species native to the Western Hemisphere. Once at the Museum I observed blooming red columbine

These two botanical gems on the National Mall have a lot to offer both human visitors as well as pollinators. On my walk home I looked up and could make out the beautiful yellow flowers high in the tops of the tulip trees (Liriodendron tulipifera) and the almost tropical white flowers of the southern catalpa (Catalpa bignonioides). So, summer is here and there are plenty of species to enjoy along the National Mall and in DC after the cherry blossoms!(Aquilegia canadensis), mountain laurel (Kalmia latifolia) and a variety of native viburnums.

Friday, May 22, 2009

Phenology and Invasive Species

I’ve been thinking about the relationship between phenology and invasive species this week as I’ve been pulling garlic mustard (Alliaria petiolata), one of the worst woodland invaders in the eastern U.S. Garlic mustard is a biennial herb; it forms a small rosette of leaves its first year, then bolts, flowers, sets seed, and dies its second year. Pulling it out at the right phenophase is the key to its control. It spreads by seed and a single plant can make thousands of seeds. It is crucial to pull it before those seeds are produced! The onset of flowering is the best time for control because garlic mustard is easy to spot (due to its white flowers), but no seeds have been formed. Right now is a great time to pull garlic mustard in the upper Midwest!

Another phenological observation about invasive species, at least in my part of the country, is that they often have a longer growing season than our native species. For instance common buckthorn and glossy buckthorn (Rhamnus cathartica and R. frangula), shrubs that invade woodlands in this region, are two of the first plants to leaf out in the spring and two of the last to drop leaves in the fall. This extended growing season may be one of the keys to their successful competitive ability. They can shade out anything growing under them and can capture sunlight and make sugar long before and after the oaks leaf out above. I’m wondering if this is a common phenomenon in species that invade forested areas. If you live near a woodland, please keep an eye out for what species green up first in the spring and drop their leaves last in the fall and let us know!

Lastly for a native species highlight, a colleague caught me in the hall this morning and said, “You have to go for a walk in the prairie, the shooters are out.” I must have looked a little confused before realizing she meant the shooting stars (Dodecatheon meadii). They are in full bloom right now in Chicago and are absolutely beautiful!

Wednesday, May 13, 2009

Why do we use first leaf rather than budburst in Project BudBurst?

It might strike you as a bit odd that in Project Budburst we generally do not record the date of budburst (!). It all has to do with keeping things simple and also making things as accurate as possible. Budburst, when you see leaf buds swelling up then “bursting” open, unfurling tiny rolled up leaves is the very symbol of spring in most northern climates. How plants actually do this, and the pattern that unfolds is quite variable, reflecting clever adaptations of plants to many different climates, habitats and stresses in the environment. Some plants such as Antelope bitterbrush, and most dogwood species, such as red osier dogwood don’t budburst at all, since their leaves are not inside buds in the winter.

They produce tiny leaves in the late summer or fall which turn red or brown in winter (and change their chemistry to protect against frost). In the spring they turn green and then expand into the mature form. Other plants such as western serviceberry, have leaves tightly rolled up, which expand out of the winter buds then later begin to unroll. Some plants have leaves which expand out of bud green, for others the leaves are various shades of red or brown when they come out of the buds (making them a little hard to see), then they turn green and unroll, or unroll first then turn green. For others there is a distinctive stage where the tip of the bud turns green, just before budburst occurs (such as American linden and black locust) . So budburst is not as simple as you might think! But this makes sense in terms of plant adaptations. Plants that begin growing when heavy frost is common such as bitterbrush, western serviceberry and chokecherry, and apples should have adaptions to frost that are less critical for species which emerge later in spring such as oaks, locusts, and elderberries.

First leaf on the other hand seems a bit more straight-forward to identify. When a leaf emerges from the bud you can clearly see the widest part of the leaf emerge, and usually see the stem (petiole) at the base. Usually the leaf then unfolds or unrolls and becomes flat, finally reaching our “first leaf” stage. How a leaf reaches this stage still can vary depending on the species. Lilacs and aspen for example first produce thick stiff leaves which emerge flat, so reach the first leaf stage quickly (and take a while to reach the all leaf stage). Red maple emerges in a droopy, limp state and takes a while to turn green and become flat.

Others such as chokecherry have leaves which emerge folded and take a while to become flat as well. It is important that we all agree on these definitions since it can effect the dates at which a plant reaches a given stage. This is also why we are working towards having better photos to document first leaf and the other stages in our phenophase field guides. So please send us your photos of first leaf and other stages as you observe them this spring. It should be a great help it making sure we are all making comparable observations.

Figure captions:

  1. Droopy new leaves of red maple
  2. Early stages of budburst for western serviceberry. Note the new leaves are thickly covered with hairs, helping protect them from severe frost.
  3. Red osier dogwood with tiny winter leaves (no bud scales)
  4. Stiff young leaves of common lilac – well adapted to heavy frosts that may occur at this time of year.


Here in the northern Rockies this week spring is still developing slowly. We had a winter storm advisory the other night again, and have snow above about 4,000’ today. Balsamroot is in full bloom now, turning some grassy south-facing hillslopes bright yellow. Most of our shrubs are at the first leaf stage, (some for weeks), and you can see many swelling flower buds. Soon as we get some warm days things may change fast!

Wednesday, May 6, 2009

Spring is at its peak right now in Chicago.

The Chicago Botanic Garden is in full bloom. In the last ten days I saw the first flowers open for several trees and shrubs, including lilacs (Syringa vulgaris), juneberry (Amelanchier canadensis), and redbud (Cercis canadensis). The magnolias (Magnolia spp.) are waning and the crabapples (Malus spp.) are just starting to open their colorful blossoms. The spring ephemerals such as bluebells (Mertensia virginica), white trillium (Trillium grandiflorum), and dogtooth violets (Erythronium americanum), rue anemone (Thalictrum thalictroides) and celandine poppy (Stylophorum diphyllum) are in full bloom in the region’s woodlands. Most of these observations were within a few days of last year’s observations of these phenophases.

We expect to see the greatest variation in the early spring phenophases. Plants that bloom early in the spring and leaf budburst for many species are tightly correlated with temperature. For plants that bloom in mid-summer, bloom time is more often cued by daylength rather than temperature. As our dataset grows, we will be able to test these predictions. Do we see a greater spread in the first flower opening date for something like Forsythia (Forsythia x intermedia), one of the first spring bloomers, compared to a grass like big bluestemAndropogon gerardii) which typically blooms in the summer.

Mayapples (Podophyllum peltatum) have almost completely expanded their umbrella shaped leaves, so I’m thinking it is about time to start hunting for morel mushrooms! Given all the rain we’ve had this spring it might be a good year for morels. And no, I’m not telling you where I go to look for them!

Wednesday, April 29, 2009

Wild weather affects wildflowers in the West

As I write this we are ending yet another snowstorm/winter advisory here in the northern Rockies region. This is a good time to consider how weather influences when plants come out in the spring. It has been a cool spring so far which is great news for skiers, and if this continues it will be a welcome relief from many years of drought and fires up here. Buttercups are the harbinger of spring and generally flower a few days after the soil thaws in the spring. This spring our first Project BudBurst observations of Buttercups were on March 17th, just a few days later than our historical average, but weeks late compared to recent years (e.g. March 7th in 2007). Just before this latest snowstorm Western serviceberry (Amelanchier alnifolia) was in full bloom. Serviceberry started blooming on April 23rd this year, within a day of its historical average. Last year by contrast serviceberry was quite late (first Project BudBurst observation of May 2nd).

It is not unusual that some species may be a bit late while others may be a bit early in a given year. Variability in when plants come out in spring is often explained by changes in temperature during the season. For example while we have had a lot of cold spells that led to the first wildflowers being late, just last weekend we had a stretch of 4 days with temperatures close to 70 or even 80 degrees, after which dozens of species of plants sent out new leaves above the ground. So it depends on when a plant normally flowers in the spring and the weather immediately before that time as to how late or early it might be in a given year (in our region it is usually the previous 10 days or so that is critical). This makes plant watching in the mountains of the West always interesting – every year, or maybe every week it is a little different!

For a total contrast consider Southern California. While it has been a bit cooler than normal this year as in the rest of the country what is most important for early wildflowers are the winter rains. So despite recent dry months there was enough moisture left from epic rainstorms in December (the famous “pineapple express”) to provide lush green growth and wildflowers covering hillslopes in early March. In San Diego I saw natural areas that were effected by the wildfires in 2007 now carpeted with pastel colors of orange, purple, and red, mostly from California poppy (Eschscholzia californica), tall phacelia, and lupines. By early April the poppies were beginning to fade but many other native annuals and perennials were beginning to bloom such as colorful bush monkey flowers (Mimulus aurantiacus).

These unusual cool wet springs are important times to see how nature can adapt to these wild swings in weather. In dry environments like grasslands, for example, these are often one of the few times that many plants provide a large crop of fruits and new seedlings. In a local grassy mountain slope I have been observing over the years for example you generally find a whole range of wildflowers which only flower during these kinds of years. This year for example we saw a white variety of the common shooting star (Dodecatheon conjugans) for the first time since 2003. This is another reason why we need years of observations to better understand these places.

The contrast in what is happening across country this year (compare these observations with those from Chicago in last week’s blog) as well as the wild variation from year to year shows why it will be so important for scientists to have data from programs like Project BudBurst to help sort things out. Check out our live maps to see how spring is unfolding across the country, and how it compares to what you are seeing in your area. I am sure more surprises await us, as the year progresses…

Monday, April 20, 2009

Spring is finally here...

Spring is finally arriving in the Chicago area! I saw the Forsythia (Forsythia x intermedia) at the Chicago Botanic Garden open its first flower on April 1 (no fooling!). This is over two weeks earlier than last year when most Forsythia first bloomed between April 17-19 in the Chicago region and more than three weeks earlier than our 2007 records (see our 2008 summary report under “Data” in the Results section of the website for more information). Coincidentally, I saw Forsythia in the same “First Bloom” phenophase in Washington DC when I was there on February 17, so their spring seems to arrive about 6 weeks earlier than ours in the northern Chicago suburbs.

Other early spring flowers in full bloom at Chicago Botanic Garden include American pasqueflower (Pulsatilla vulgaris), some early daffodils (Narcissus spp.), and, as my nose reminds me, Red maple (Acer rubrum). Maples are a common cause of spring allergies. I was in Galena in far northwestern Illinois on April 11 and saw some Bloodroot (Sanguinaria canadensis) with several open flowers; one of my favorite harbingers of spring!
A friend in central Tennessee found his first morel mushrooms of the year last week. Some of the morel hunting lore about when to look for these tasty treats include:

  • When the Lilacs start to bloom
  • When oak leaves look like mouse ears
  • When the first Dandelions go to seed
  • When the Mayapple leaves have fully expanded into their classic umbrella shape

I checked our Project Budburst live maps for Lilacs, Dandelions and Mayapples to see if we had any data to confirm this folklore, but we do not have many submissions from Tennessee yet. If you’re in that region, let us know if you’re seeing Lilacs blooming or Dandelions going to seed!

Lastly, I’d like to send out a quick reminder that we are looking for good photographs of different phenophases for many species. As you go through the species phenophase field guides, you may see empty photo frames with “Photo Needed! Share your photo of this phenophase.” If you have a good photo of that species and phenophase that you would like to share, please send them to We will be happy to include your photo credit on the Website. Visit our Photo Gallery for complete information.

Thanks to all of you who are watching plants and submitting your observations! These data are helping us get a much clearer picture about how plants are responding to different climates around the U.S. This will help us predict how plants will respond to a changing climate.