This Just In – Blue Wild Indigo Now Blooming

I hope to post more pictures in a few days, when the iris series is done, but if I wait ’til then these plants will be done blooming, so go looking for them now. Baptisia australis (Fabaceae) is not often see in Maryland. It likes the bedrock terraces in the Potomac Gorge. Be careful of high, fast-moving water and poison ivy. There isn’t much else blooming now, so the color really stands out.

More pics soon.

Desert Fabs

Fabaceous plants, that is. For the next several weeks I’m likely to be posting back-and-forth between finds in Anza-Borrego and in the Maryland piedmont.

Astragalus crotalariae
Salton milkvetch

Astragalus is the largest genus of plants known, with about 3,000 species, around 350 of which are native to North America. A. crotalariae has a limited range, found only in the Sonoran desert, in Northern Mexico and a few parts of southern California and southwestern Arizona. It’s a perennial that grows to about two feet tall.

Lupinus arizonicus
Arizona lupine

There are about 200 species of lupines worldwide, with maybe 70 or so in California. It’s hard to say how many are in the Sonoran Desert, since many of the species have multiple subspecies. A quick glance at several internet sources leads me to think that maybe there are one to two dozen.

L. arizonicus is native to the Sonoran and Mojave deserts. It’s a desert ephemeral, growing only in years when there’s been enough rain, and reaching to about a foot and a half tall, Depending on which authority you consult there are several subspecies; interestingly, several of the subspecies have their own varieties, for example Lupinus arizonicus ssp. arizonicus var. arizonicus and Lupinus arizonicus ssp. arizonicus var. barbatulus. I have no idea which one is pictured here.

Lupinus sparsiflorus
Coulter’s lupine

I found a long swath of these southwest of Borrego Springs, on the other side of the mountain range just outside Azna-Borrego Desert State Park proper, along the shoulder of San Felipe Road. I wasn’t sure at first if they were Arizona lupine or one of the other species.

The color was different, but that’s an unreliable characteristic. The plants were shorter and smaller overall, but that could have something to do with local growing conditions. Then  I found a good description of both species. L. arizonicus has mostly glabrous (smooth) leaves, while L. sparsiflorus is ciliate (hairy), especially at the margins.

Psorothamnus schottii
indigo bush, Schott’s dalea

This six foot tall shrub has a similar range to the Astragalus (that is, rather limited parts of the Sonoran Desert). When it blooms it’s just covered in lightly fragrant blue-purple flowers. And bees.

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

A Beautiful, Useful Pest in Iceland

Lupinus nootkatensis
Nootka lupine, Alaskan lupine
Icelandic: Lúpína


My recent post about yellow flag iris (“A Beautiful, Useful Pest”) was written in the lounge at Dulles International Airport while I waited for my flight to Iceland. It struck me as funny, then, that the next day, when we parked our rental car near a trailhead and started hiking, that the first flowers I noticed were the Nootka lupines. They were everywhere – wide swaths of blue-and-white flowers ascending the slopes of Mount Esja.

There was so much of it, I wondered if it was an alien invasive. In my limited experience, it’s unusual for native plants to form such massive colonies. Was this another beautiful, useful pest?

Short answer: yes. It’s native to the coastal areas of northwestern North American, and is alien to Iceland. But it didn’t sneak in via packing on a cargo ship or by hitchhiking on other agricultural material. It was introduced, possibly as early as the late 1800s (I’ve read conflicting stories), and certainly by the mid-1900s, when it was planted deliberately and extensively by first the Icelandic Forestry Service, and later by the Soil Conservation Service, to help with land reclamation.


You may recall from the previous post that after Icelandic settlement, deforestation and overgrazing led to lifeless soil, which is easily eroded and transported by winds. The Nootka lupine grows fast and roots well, keeping soils in place. It’s perfectly suited to Iceland’s cool, wet growing conditions. And like most members of the Fabaceae (pea family), it takes nitrogen from the air and fixes it in the soil, which together with decaying plant material (from dead lupines) results in soil fertile enough for native plants to colonize. It’s even thought to have helped with the problem of sandstorm-induced road closures in the eastern parts of the country.

But (of course there’s a “but”), it’s too aggressive. It grows tall enough to form a canopy that blocks sunlight to mosses and lichens (which are important pioneer species). It can invade nearby plant communities, outcompete the natives, and form monocultural stands. So yes, it exhibits the usual alien-invasive characteristics.

There’s a little more good news, though: studies have shown that in some sites, lupine colonies will eventually decline to the point where they no longer out-compete other species. It seems that if managed correctly, the Nootka lupine will continue to be a valuable tool for soil reclamation.

lupines on the lower slopes of Mt. Esja

for more information:

Biological Diversity in Iceland (The Icelandic Institute of Natural History; go to page 10 for the case study of Nootka lupine)
Alaskan “Wolf” Invades Iceland (Reykjavik Grapevine, August 25, 2011)
Invasive purple flower Impacts Iceland’s Biodiversity (
Invasive Alien Species Fact Sheet (