The Fabaceae (part 2)

Some fabaceous plants in the Maryland piedmont bloom in the spring, but most of the family wait until high summer to get going. The bloom times stated below are approximate – especially early in the season, when they can vary by one or two weeks.


By my observations, the earliest blooming fab in the Maryland piedmont is the redbud (Cercis canadensis), a lovely understory tree that usually starts flowering in May, about the time the dogwoods are finished. It’s a nice addition to a native landscape garden except for one thing: it fruits profusely. The pods are easily raked up with autumn leaves, but invariably some will escape your attention and the following spring you’ll be pulling redbud seedlings out of your garden. (Ask me how I know.) Also, it can grow lanky and the wood is somewhat weak. The tree (and therefore your garden) benefits from thoughtful pruning.


Black locust (Robinia pseudoacacia) can be a spectacular tree in May when flowering, if it gets enough sunlight. But more often you’ll see it in mixed deciduous woodlands, growing very straight and tall with the blossoms hidden in the canopy. The wood is incredibly rot-resistant, making for long-lasting fencing, and has very high BTU value. However, the trees blow over easily and will even shear off horizontally in the right conditions. Again, ask me how I know… At my previous house any time a black locust would break off, I’d cut up the wood for the fireplace but leave the stump for the birds. An eleven-foot stump in my front yard served as a feeder for pileated woodpeckers. Sometimes I miss that place.



a great specimen of black locust growing at wood’s edge —>






Another May bloomer, wild blue indigo (Baptisia australis) is on the RTE* watchlist (S3) in Maryland. I know of two distinct stands of it along the Potomac, where it grows with Culver’s root (Veronicastrum virginicum). I grew wild blue indigo at my previous house, and it is a profuse bloomer. It’s a stunner in the garden but the seedpods are so numerous and heavy, they pull the plant right over. And they germinate in great numbers. If you remove the pods, though, it’s a well-behaved plant.



seedpods on Baptisia australis





Hylodesmum glutinosum (formerly Desmodium glutinosum; pointed-leaf tick-trefoil) blooms in early July. This picture was taken in western New York state. I’ve only seen it here in the Piedmont in one place along the Cabin John Trail, where every year I miss seeing it bloom. It seems to like deep woods and moist soils, and often grows in association with lopseed (Phryma leptostachya). The tick-trefoils can be tricky to identify, but this one is easy because of the large, pointy leaflets (three per leaf):20150707-20150707-_DSC0005






Also blooming in July, more or less, is the closely related Hylodesmum nudiflorum (formerly Desmodium nudiflorum; naked-flower tick-trefoil). This one is easy to distinguish from other tick-trefoils because there are no leaves on the flowering stem. It grows in more or less the same conditions as the pointed-leaf tick-trefoil, except maybe it wants a bit more sun.


Clitoria mariana (butterfly pea or Atlantic pigeonwings) blooms from late June into August. I’ve seen it in a few places in the Potomac gorge, never in large numbers (usually just one plant growing alone), mostly in open, rocky places. The plants are vining, and stay fairly close to the ground. Butterfly pea is endangered in New Jersey and Pennsylvania.



Panicled tick-trefoil (Desmodium paniculatum) blooms in late August. It grows in moist to dry soils in sun to part shade, and does well in disturbed areas.





Lespedeza virginica (slender bush-clover) is sadly not nearly as common as its alien cousin, Lespedeza cuneata (Chinese bush-clover). You’ll often see the two growing together in dry soils in sunny areas, blooming in August. Slender bush-clover is threatened in New Hampshire and Wisconsin.


Senna hebecarpa (wild senna or wild cassia) is another August blooming plant. It grows up to six feet tall, with rigid stems that seem almost to lignify, and often in such masses that it could be mistaken for a shrub. It’s endangered in Massachusetts and New Hampshire, special concern in Connecticut, threatened in Vermont, and historical in Rhode Island. Wild senna has a nearly identical cousin, S. marilandica, that is rare (S3) in Maryland; Maryland Biodiversity Project has no records for it.


Amphicarpaea bracteata (hog-peanut) is a shortish vine that stays low, twining through other plants, blooming in late August.




And pink fuzzybean (or pink wild bean, or perennial woolly bean; Strophostyles umbellata) is another August blooming vine. It’s endangered in New York and threatened in Rhode Island.



*Rare, Threatened, Endangered

The Fabaceae (part 1)


According to the Biota of North America Project, the pea family is second only to the aster family in number of native species in North America, with 1,277 species. Worldwide it’s the third largest plant family, with about 18,800 species in over 600 genera.

The Maryland Biodiversity Project has 161 listed pea family species, though many are alien. Not quite half of these species are present in the Maryland piedmont.

The plants can be herbaceous (annual, biennial, or perennial) or woody. Most of the North American species share these characteristics (as always, there are exceptions):

  • compound leaves, with three to many leaflets, which can be arranged pinnately, bi-pinnately, or palmately
  • in some species, the leaflets are modified into tendrils
  • the leaves usually have stipules, though the stipules often shrivel and fall off early in the plants’ annual growth cycle; in some species, the stipules are modified into thorns



trifoliate leaves of Amphicarpaea bracteata (hog-peanut)






Lupinus nootkatensis (Nootka lupine) with palmately compound leaves





pinnate leaves of Chamaecrista species




There are three generally recognized subfamilies of the Fabaceae: Faboideae, Caesalpinoideae, and Mimosoideae. Faboideae flowers share the following characteristics:

  • a calyx consists consisting of 5 sepals, fused together
  • a corolla consisting of 5 petals, in a bilaterally symmetrical arrangement whose shape suggests a butterfy


These flowers have their own terminology: the uppermost petal is the banner, the two side petals are the wings, and the two bottom petals, fused together, are the keel.

Hylodesmum nudiflorum (naked-flower tick-trefoil)

Flowers in the Caesalpinoideae are much the same, except that the two bottom petals (keels) are not fused.


Cercis canadensis (redbud)


Fabaceous fruits are usually either legumes or loments. Botanically, a legume is a type of dry fruit that usually opens along two seams at maturity (like peapods). A loment is a legume with a jointed pod.



loment of Desmodium paniculatum (panicled tick-trefoil)


Of course this family is of major agricultural importance. Fabaceous foods include peas, beans, peanuts, lentils, soybeans, and tamarind. Alfalfa and clover, among others, are significant forage crops, for honey bees as well as our domesticated herbivores. And just as the euphorbs have latex, some fabs have natural gums, widely used in food manufacturing, cosmetics, and pharmaceuticals.

next time: fabulous fabaceous wildflowers

The Euphorbiaceae, part 2

“Euphorbia” sounds like “euphoric”, so of course I spent a little time researching it. I found a detailed account that goes back to the Natural History of Pliny, first published in AD 79. Seems the plant was named for a physician, Euphorbus. “Euphoric” can be translated as “well-fed”; it’s from the Greek “euphoros”, which means “healthy”. The whole story, as well as much more detailed information about all aspects of the family, can be found at the Euphorbia Planetary Biodiversity Inventory Project website.


As for euphorbs in Maryland, we have maybe 40 species, roughly half of which are native. About a dozen of those natives are in the Maryland piedmont. And yet I’ve only seen one: flowering spurge, Euphorbia corollata. You might recognize it as the current wallpaper image on my blog. It’s also the white flowering plant I’m shooting in the current banner photo, also pictured below:


This was a magnificent specimen, standing about two and a half feet tall, growing right out of a cleft in the rock along the Billy Goat A trail near Great Falls. The plants seem to like rocky places, at least in the Potomac gorge. Watch for them blooming in August, also on Billy Goat B and at Serpentine Barrens Conservation Park.


Those white parts aren’t petals, of course; they’re bracts. The actual floral parts are contained in the cyathia in the very center. The whole structure measures about half an inch across.

This is a truly graceful plant, one of my favorites. I think it would be a lovely motif on a fabric.

The Euphorbiaceae, part 1


The spurge family is one of the largest in the world, though exactly where it ranks is difficult to say for sure. There are almost 2,000 species in 300 genera worldwide (except the arctic and Antarctica). Most are tropical, and many are succulent, resembling cactuses; others are typical annual or perennial forbs, and a few are woody. It’s a family of great morphological diversity.

It’s also a family of great economic importance. Poinsettias are one of the most widely grown ornamentals. Natural rubber is made from the sap of Hevea brasiliensis. Cassava isn’t much known in the US, except in the form of tapioca, but it’s a staple food in many tropical regions; it comes from Manihot esculenta. The roots are eaten as a vegetable or dried and made into a flour.

Castor bean, Ricinus communis, is a particularly interesting plant, appearing on (or topping) lists of most poisonous plants in the world. It’s grown as an ornamental for its foliage, but is considered invasive in many places, and is highly allergenic, rating 10 out of 10 on the Ogren Plant Allergy Scale. The oil extracted from the seeds has industrial and medicinal uses, but the raw seeds contain a potent poison (ricin). Castor oil is even used in the manufacture of a food additive, polyglycerol polyricinoleate.


Species in the genus Euphorbia tend to have minute flowers. An involucre contains all the reproductive parts, collectively referred to as the cyathium. The cyathium consists of one carpellate (female) flower and several or many staminate (male) flowers surrounded by bracteoles (miniature bracts, or modified leaves). In many species there will be lipped glands (extrafloral nectaries) on the outside of the cyathium. This closeup of a poinsettia shows more than a dozen unopened cyathia with their nectaries, surrounded by the highly colored bracts.

Another characteristic common to many (but not all) euphorbs is the presence of a milky sap (latex) in the stems. Generally it’s caustic, more or less so depending on the species. It’s one field test to use when trying to identify plants, but not definitive, as ten percent of flowering plants contain latex*. At any rate, don’t get it on your skin.

Of course there are euphorbs in the Maryland piedmont, otherwise I wouldn’t be writing about them. More on those next time.

*Latex: A Model for Understanding Mechanisms, Ecology, and Evolution of Plant Defense Against Herbivory

Native Umbellifers (Apiaceae, part 4)

Now that you know a little about umbellifers, have a look at these native wildflowers. Some of them are not as obviously umbelliferous as others; you would almost have to look at them with a hand lens to tell. (The bloom times mentioned below are for the Maryland Piedmont, based on recent years.)


Erigenia bulbosa
Harbinger of spring, aka salt-and-pepper, blooms as early as mid March, and maybe as late as mid April. It’s listed S3 (watchlist) in Maryland, is endangered in New York and Wisconsin, and threatened in Pennsylvania. It’s a perennial of rich woodlands, with flowers in compound umbels; there are 1-6 flowers per umbellet and 1-4 umbellets per umbel*. The near umbel in this picture, with four umbellets, is about the width of a nickel.


Zizia aurea
Golden alexanders can bloom as early as late March and if they start later, might last ’til late May. This species is also S3/watchlist in Maryland, and is listed as special concern in Rhode Island. The compound umbels typically have around 12 umbellets, each with about 21 flowers*.


Osmorhiza claytonii
I’ve seen sweet cicely blooming as early as early April and as late as mid May. The plants tend to be in flower rather longer than the previoius two species. There are no conservation issues. This species also has compound umbels, with each umbellet sporting 4-7 flowers**.


Chaerophyllum tainturieri
Hairy-fruit chervil generally blooms from about mid April to about mid May. Each flower measures around 3/32″ wide. This is another species whose flowers are in compound umbels. There are no conservation issues.

clustered snakeroot closeup


Sanicula odorata
Clustered snakeroot blooms for a long period, starting as early as late April and lasting maybe ’til mid June. It’s threatened in Massachusetts and New Hampshire but abundant in the Maryland Piedmont. In late May it seems to be a dominant understory forb, growing in great swaths in the woods along the Billy Goat B and C trails and the Cabin John trail. There are 20-60 flowers in each umbellet, and 1-5 umbellets per one-half inch wide umbel*.



Cryptotaenia canadensis
Honewort also blooms for a long period of time, typically from late May to late June. Once again the flowers are in compound umbels, with 3-10 flowers per umbellet and 3-10 umbellets per umbel*. Like clustered snakeroot it grows profusely in Maryland piedmont woodlands.


*from Dr. John Hilty’s wonderful Illinois Wildflowers site.
**Minnesota Wildflowers