Braking for Wildflowers Again


Steve and I were in Joshua Tree National Park recently. There wasn’t a super bloom this year, but there were still a few wildflowers. Mostly they were the Sonoran and Mojave desert plants that I wrote about this time last year, and the year before that.

Heading south on Pinto Basin Road toward the Cholla Garden, I spotted large, dark green leaves on plants growing by the side of the road. What the heck, is that datura? I thought. Then, “Steve, slow down!”

And he did, and pulled over, and I jumped out and had a look.

Yes, they were Datura, but all the flowers were spent or closed. So the next day we went back, and drove slowly (whenever no cars were behind) until I spotted some open flowers. And he pulled over again, and had a little catnap in the car while I got on my belly on the sandy roadside shoulder and snapped some pictures.


There are two species of datura in JOTR, D. wrightii (sacred thorn-apple) and D. discolor (desert thorn-apple). This one is the former. Other common names for the various Datura species include jimsonweed and angel’s trumpet; there are dozens more, including moon lily, moon flower, belladonna, devil’s trumpet, deadly nightshade, thorn apple, mad apple, hairy jimson weed, stink weed, green dragon and locoweed1, and toluaca2.

These spectacular flowers measure about 15 cm long, and the plants can grow to a meter or more tall and almost two meters wide. All parts of the plants are poisonous, not unusual for plants in the Solanaceae.

The Solanaceae, like the Apiaceae (see Tasty Umbellifers and Poisonous Umbellifers), is notable for producing both foods (eg, tomato, potato, chili pepper, and eggplant) and poisons (eg, belladonna, tobacco, mandrake, and henbane).

We have a datura here in the Maryland piedmont, D. stramonium [right], but it’s an invasive alien that can form large, nearly monocultural stands. There’s an especially bad infestation on an islet in the Potomac just upstream of the American Legion bridge [below].


1DesertUSA
2Calflora

Similar Species in Similar Families

Phacelia species. Oh, that blue!

Last year during my Death Valley trip, Cryptanthas drove me crazy. There are something like 120 different species, many of which can only be reliably distinguished by examining the minute nutlets.

Cryptantha species

 

 

 

I saw plenty of Cryptanthas in Anza-Borrego, too, and decided not to bother much with them. Neat little flowers, but I would just have to accept that I wouldn’t be able to identify them fully.

a different Phacelia

 

 

 

Then there were the Phacelias. I saw plenty of them, too. Turns out there are about 170 species of Phacelia in North America. Not all of them are found in the Sonoran Desert, of course, but enough of them are.

Phacelia crenulata.

Phacelia nashiana. Unless it’s Phacelia minor.

Like Cryptanthas, the Phacelias are notoriously tricky to identify. I spent hours poring over botanical descriptions but my pictures contain only so much information, and often not the right sort. I didn’t get very far.

A different Cryptantha; the flower is about 1 mm wide.

 

 

I gave up when I discovered that there’s a species named Phacelia cryptantha.

Phacelia campanularia. I think. I hope.

 

 

 

 

 

While researching these plants, I tripped across another issue. Seems that authorities don’t quite agree on which family to place the genus Phacelia in. At one time, there were two separate but closely related families, Boraginaceae (borage) and Hydrophyllaceae (water-leaf).

Pholistoma membranaceum, Hydrophyllaceae. Unless it’s Boraginaceae. Or the Hydrophylloideae subfamily of Boraginaceae.

 

Recent research has resulted in the Hydrophyllaceae being considered a subfamily of the Boraginaceae, called Hydrophylloideae.  Not all authorities recognize this distinction, though, and research is ongoing. It’s another one of those areas of taxonomic uncertainty.

Amsinckia species, either A. tessellata or A. intermedia, Boraginaceae

Emmenanthe penduliflora, Hydrophyllaceae. Or Boraginaceae. Whatever.

 

 

 

 

 

 

 

 

 

 

 

 

In an attempt to make sense of all this, I went through several books* to get good technical descriptions of the two families’ characteristics, and came up with this chart:

Boraginaceae Hydrophyllaceae
form: forbs; rarely shrubs or trees forbs; rarely subshrubs
overall rough textured, hairy overall small, hairy
leaves: alternate alternate; rarely opposite
simple simple, sometimes compound
no stipules no stipules
often entire mostly lobed, rarely entire
coarsely hairy often hairy or stiff-hairy
inflorescence: helicoid or scorpioid cyme scorpioid cymes or flowers borne singly
flowers: often blue or white mostly blue, purple, white
regular (radially symmetrical) regular (radially symmetrical)
bisexual bisexual
5 sepals, separate 5 sepals, separate or fused
or deeply cleft to appear separate or deeply cleft to appear separate
5 petals, fused 5 petals, fused, often w/ appendages inside
5 stamens fused to corolla, alternate with petals 5 stamens fused to corolla, alternate with petals
? nectary disk present
anthers w/ longitudinal slits anthers w/ longitudinal slits
2 carpels, united, often 2 lobed 2 carpels, usually united
locules 4, usually 1-2 locules
ovules 1 per locule ovules 2 – many
ovary superior ovary superior
style 4-lobed style 2-lobed
stigma 2 lobed stigma capitate
fruit drupe or nutlets capsule

I’m not sure it helped, but it was an interesting exercise.

Phacelia cryptantha?!

 

Speaking of Phacelias, three of them are native to the Maryland Piedmont. Yesterday I found one blooming profusely and one of the others budding up. More on them in a few days.

another Cryptantha!

Phacelia and Amsinckia growing together, the devils.


*Botany in a Day, Thomas J. Elpel
Contemporary Plant Systematics, 3rd. ed., Dennis W. Woodland
How to Identify the Flowering Plant Families, John Philip Baumgardt
Photographic Atlas of Botany and Guide to Plant Identification, James L. Castner

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.

Desert Shrubs and “Trees”

There are so many interesting plants in the desert, and not just forbs. In mid March when I was at Anza-Borrego, shrubs were in full bloom, too, and one really unusual tree-like plant was just starting. And then there were the palms.

Encelia farinosa

This shrub goes by the common names brittlebush, incienso, and gold hills. I saw them all over the place, standing like good omens, saying “welcome to Anza-Borrego!” with their cheery yellow flowers. Brittlebush is in the Asteraceae, of course, and can be found on hillsides and slopes in the Sonoran and Mojave deserts, at elevations from below sea level to 3,000 feet above or more, depending on which authority you consult.

Justicia californica

Known commonly as beloperone, chuparosa, and hummingbird bush, this species is found mostly in the Sonoran Desert, with a few occurrences in the Mojave. It can grow to six feet tall and twelve feet wide. Justicia, a genus in the Acanthaceae, has over 600 species, only a few of which are found in North America. Of those, the most widespread is Justicia americana, which ranges from Texas to Quebec; there are vast stands of it in the Potomac River every summer.

Fouquieria splendens

Ocotillo is such an unusual plant, it deserves a post all its own, but I’m short on time. Each stem can grow to 20′ tall, and a mature plant can have dozens of stems. They bear leaves only after sufficient rain. The bright red flowers attract hummingbirds.

From a distance you might think they’re a type of cactus, but they aren’t even closely related. (Going up on the taxonomic tree, cacti are in the order Caryophyllales, while ocotillo is in the Ericales.) There are only eleven species in the genus Fouquieria, which is the only genus in the family Fouquieriaceae. Ocotillo grows on slopes and hillsides, ranging from the southern Mojave through the Sonoran and Chihuahuan deserts.

Speaking of hummingbirds, while I was shooting some low-growing plant or other I heard this loud buzzing, and looked up to see this —>
That’s a black-chinned hummingbird, Archilochus alexandri. Once more I was both thankful to have a zoom lens, and wishing I had a longer zoom lens.

One of the greatest wildflower displays in Anza-Borrego was along the Borrego Palm Canyon trail, a nice, easy hike up a gentle grade that leads to actual running water and a big group of Washingtonia filifera, California fan palm. This plant in the Arecaceae can reach heights of 60 feet in the presence of open water. Click on the picture to see it larger; note the people on the boulder for scale, and how the brittlebush and chuparosa are growing together. California fan palm is native to the Sonoran and Mojave deserts, and is the only palm native to western North America.

Four O’Clock

So if the five petals of a desert sand verbena flower (see previous post) are not really petals, what are they?

In order to answer that, I’ll need to review some basic flower terminology.

The reproductive organs of a flower (the pistil and stamens) are usually surrounded by petals, which are modified leaves, often brightly colored. Collectively, the petals form an inner whorl of parts that is called the corolla.

There is usually an outer whorl, too. This consists of sepals, modified leaves that are often, but not always, green, and surround the flower bud as it forms. Collectively, the sepals are known as the calyx.

Taken together, the calyx and corolla are called the perianth.

In some species, there’s another set of modified leaves at the base of the flower, in addition to the calyx and corolla, that are called bracts. The bright “petals” of poinsettias and flowering dogwood are examples.

Detailed, technical descriptions of flowers in the Nyctaginaceae will mention the perianth, but say nothing of the petals, because there are none.

What looks like five petals on the sand verbena flower is actually a single five-lobed tube formed by five fused sepals. This is typical for flowers in the Nyctaginaceae. Some sources state that the perianth comprises fused tepals; think of a tepal as an intermediate between a petal and a sepal.

Flowers in this family often have bracts as well; Bougainvillea is an example. The reproductive parts usually consist of a single pistil and five stamens.

The inflorescence is typically a cyme. Most species are forbs, though there are a few shrubs, trees, and vines. There are about 300 species in about 30 families, found mostly in tropical and warmer temperate regions of the world.

Several species of plants from the Nyctaginaceae are found in the Sonoran Desert, including the following.

Allionia incarnata

Trailing windmills is a forb with a vine-like habit, growing along the ground. It can be either annual or perennial. The species is found in the Chihuahuan, Sonoran, and Mojave deserts, and the southern part of the Great Basin Desert. There are two varieties, incarnata and villosa. I believe this one to be the later based on location reports in CalFlora and the USDA PLANTS Database. I don’t have sufficient detail to identify it based on plant characteristics.

This flower consists of three clustered perianths. Unlike most other species in the Nyctaginaceae, trailing windmill flowers stay open all day. Most species in this family have flowers that open late in the day, hence “four o’clock”.

 

Mirabilis laevis

Depending on which authority you consult, there are four to six varieties of this small shrub, commonly called wishbone bush or wishbone plant. I believe this one to be  retrorsa, but lack sufficient detail to say for sure; it could also be villosa. Both have similar ranges in the Sonoran, Mojave, and Great Basin deserts.