Tag Archives: Cruciferae

Primitive Mustards: Thelypodium in the Bodie Hills

Thelypodium laciniatum

Thelypodium laciniatum

Thelypodium (thely-POD-ium) is a genus of about 29 relatively stunning species in the mustard family (Brassicaceae, a.k.a. Cruciferae). The genus ranges across much of the desert and intermountain west, Columbia Basin, southwestern United States and northern Mexico. Four species occur in the Bodie Hills, Mono Basin, and adjacent areas: T. crispum, T. laciniatum, T. milleflorum, and T. integrifolium subsp. complanatum. A fifth species, T. flexuosum occurs to the north and east (as close as Carson City), but has not been documented in the Mono-Mineral-Lyon county area.

Thelypodium flowers (in our area) are mostly whitish, with slender petals. In most of our species the flowers are packed into a dense, tall, slender raceme with many dozens of flowers (but fewer flowers in a short inflorescence in T. integrifolium). In fruit, the plants develop long, slender, spreading or ascending siliques (fruits), parts of which often persist long after they have opened and scattered their seeds. I’ve noticed that late in the year, or early the following spring, these tall, dried-out stems with the remains of old fruits may be much easier to spot from a distance than fresh plants of the current growing season — especially in early morning light or against a dark background.

For more than a century, taxonomists studying Thelypodium and related plants have found it difficult to decide what species to include in this genus as opposed to other allied genera. Most of the species are fairly easily defined; the generic boundaries are not (Al-Shehbaz 1973). Little surprise, then, that learning to recognize Thelypodium as a genus is best accomplished by learning to recognize some of its species. The genus becomes recognizable once you have a feel for the differences and similarities among its species. Several other genera share various characteristics with Thelypodium, and together these are recognized as a larger group, the tribe Thelypodieae (thelypod-EE-ee-ee). Other genera of Thelypodieae found in this area include Stanleya, Caulanthus, Streptanthus, and Streptanthella.

The name Thelypodium is based on the Greek: thēlys for ”female” and podion, a diminutive for “foot.” This refers to the distinct “gynophore” in most species of Thelypodium. A gynophore is a kind of stalk or stipe (or foot) that raises the ovary and fruit above the receptacle of the flower. Payson (1923) asks, “What is the significance of this stipe? Recent students of the Cruciferae are nearly unanimous in the belief that this family has been derived from the Capparidaceae [Caper family, also treated as part of Cleomaceae] or from capparidaceous-like ancestors. . . . In the Capparidaceae a stipe [or gynophore] is almost universally present and is often very long. Granting this relationship between the two families, the presence of a stipe in the Cruciferae, in which it is not of common occurrence, must be considered either a primitive character or an atavistic [ancient or ancestral] variation. For the sake of argument . . . the stipe in this group will be assumed to be a primitive characteristic.” So, Thelypodium retains what is considered a primitive structure (the gynophore) in a family that has evolved (eventually losing its gynophores) and diversified with great success worldwide.

Photos showing the pedicel, receptacle, gynophore, and fruit in Thelypodium (left) and Cleomella (right). The presence of a gynophore in Thelypodium suggests an evolutionary link between mustards (Brassicaceae) and capers (Cleomaceae).

Upon finding a suspected Thelypodium in the field, here are the characteristics to look for (and photograph, if you’re posting to iNaturalist, Calflora, or CalPhotos):

  • Habitat: Where is it growing? On a rocky cliff or outcrop? In loose, dry, sandy or silty soil? In or near a moist, perhaps alkaline meadow, spring, or creek?
  • Leaf shape: These plants are biennials and the basal leaves wither as the flowering stems develop, so you will most often be looking at cauline leaves (leaves on the stems). The cauline leaves become smaller and narrower, with shorter petioles and less-developed lobes or teeth higher along the stem. Look at the lower and mid-stem leaves: are they deeply lobed, merely toothed, or entire? Are the leaf blades petioled or sessile?
  • Inflorescence shape: Is it a tall, elongated raceme of many flowers, or are the flowers and fruits condensed into a short, almost tuft-like raceme at the end of long branches?
  • Pedicel shape: The pedicel is the little stalk from the stem to the base of each flower. In flowers that have gone to fruit, or are beginning to produce fruits, is the pedicel spreading (more or less straight out from the stem)? Or is it bent, curving upwards?

Thelypodium crispum (Wavy-leaved thelypody) may be the commonest of the four species in the Bodie Hills, but it has the narrowest geographic range overall. It is found from Inyo and Esmeralda counties north along the eastern Sierra Nevada and western Great Basin to Lassen and Washoe counties. It grows mostly in moist, alkaline or mineralized, sandy or gravelly soils near meadows or springs, but occasionally also in sagebrush scrub or pinyon-juniper woodland. I’ve seen it also on subalpine glacial moraines above Virginia Lakes.

Thelypodium crispum

Thelypodium crispum

Thelypodium crispum

Thelypodium crispum

It’s generally the shortest Thelypodium in this area — typically under 3 feet tall, often just 1–2 feet tall. Mid-cauline leaves are narrowly lance- or arrow-shaped, sessile, and clasping the stem. The leaf margins are entire (neither lobed nor toothed), and may be either flat or wavey (leaves with wavey margins are called “crisped”; hence T. crispum). The fruiting pedicels are ascending, often pressed against the stem, and the fruits are straight, stiff, and less than 2 inches long. T. crispum is similar to and sometimes misidentified as T. brachycarpum. The latter occurs mostly in far-northern California and southern Oregon; its fruiting pedicels are horizontally spreading.

Good places to look for T. crispum include Travertine Hot Springs, Coyote Spring, other hot or mineralized springs, and Long Valley (east of Mammoth).

Thelypodium crispum

Thelypodium crispum

The next two species may appear similar from a distance — larger plants of both may stand as tall as a person, rising above the surrounding shrubbery, with striking, many-flowered racemes of white (or creamy- or greenish-white) flowers. Both have slender fruits 1.5–4 inches long, that tend to bend, curl, or droop when fully grown. On closer inspection, these two are easily recognized by differences in leaf shape, pedicel shape, and habitat.

Thelypodium laciniatum (Cutleaf thelypody) is a cliff-dweller. It favors rocky crevices and outcrops, and its distribution suggests it may favor volcanic rather than granitic substrates. Fruiting pedicels are spreading to just slightly angled upward, not strongly curved. The lower leaves are laciniate, i.e. irregularly lobed, often deeply so. The inflorescence may contain dozens to well over a hundred flowers. Plants may be few-stemmed or be virgately branched, i.e., with numerous stems fanning out from the base.

Thelypodium laciniatum

Thelypodium laciniatum often has many stems (but this may be 2 or 3 plants).

Thelypodium laciniatum

Thelypodium laciniatum is a cliff-dweller.

Thelypodium laciniatum

See how the pedicels of Thelypodium laciniatum are all straight? (yellow arrows). Except for one that read the wrong instructions.

Good places to look for T. laciniatum include the cliffs east of Hwy 182 and the East Walker River 1.1 road miles north of Bridgeport Reservoir Dam, cliffs above NF-028 at The Elbow, and the Owens River and Lower Rock Creek gorges. You may need binoculars for a good look at these plants.

Thelypodium milleflorum (Many-flowered thelypody) inhabits  sandy or deep silty soils. The pedicels are bent strongly upwards (this becomes more apparent as the flowers go to fruit, so early in the season look around for last year’s stems). Aven Nelson (1911), in his description of this species (from collections in Idaho), says the fruits are “normally strongly ascending or suberect, but often irregularly spreading as if from their weight.” The lower leaves are dentate—toothed or shallowly lobed, but not deeply lobed. The epithet “milleflorum” suggests it has “a thousand flowers.” Nelson offers no explanation and I haven’t counted, but clearly there could be several hundred flowers on a robust plant with several inflorescences (and the same could be said for T. laciniatum). This is a CNPS “List 2B.2” plant—”Rare or Endangered in California, common elsewhere. Fairly endangered in California.”

Thelypodium milleflorum

Sometimes Thelypodium milleflorum grows in dense stands like this; other populations are more dispersed.

Thelypodium milleflorum

Young stems of Thelypodium milleflorum. These will grow much taller and the racemes will develop many more flowers over the next 2 to 3 months.

Thelypodium milleflorum

Thelypodium milleflorum in soft, silty-sandy soil at the edge of a pinyon pine grove. It’s done flowering, but the fruits are still green.

Thelypodium milleflorum

See how the pedicels of Thelypodium milleflorum all curve up? (yellow arrows).

Good places to look for T. milleflorum include Goat Ranch Cutoff, Dobie Meadows Road, and probably other sandy places around the north and east margins of Mono Basin.

Thelypodium integrifolium is the most widespread of the species here — with five subspecies, its range extends throughout much of the desert and intermountain west. In the Bodie Hills, however, we have only one subspecies: T. integrifolium subsp. complanatum (Foxtail thelypody), which is the one seen from the eastern Sierra across most of central and northern Nevada. Its inflorescences are short and strongly congested at the ends of long, nearly naked branches. The flowers are usually a pale lavender-purple, sometimes white. It grows in moist to wet, alkaline or silty soils of meadows, creeks, and sometimes adjacent uplands.

Thelypodium integrifolium

Thelypodium integrifolium

I’ve seen it only along a wet ditch beside the road from Fletcher to Aurora (in Nevada), but there are a few other records from the Mono Basin. This is another CNPS “List 2B.2″ plant—”Rare or Endangered in California, common elsewhere. Fairly endangered in California.”

Thelypodium integrifolium

Thelypodium integrifolium

Not Thelypodium

Here are a few other plants that could trick you into thinking they might be a Thelypodium:

Stanleya pinnata

Stanleya pinnata is a very primitive mustard (with long gynophores). It has bright yellow flowers and pinnately lobed lower leaves.


Cleomella hillmanii (left) and Peritoma serrulata (right) are in the Cleomaceae, from which the primitive mustards may have evolved. These too have gynophores. Their compound leaves (with three leaflets) are very different from Thelypodium leaves.

Al-Shehbaz, Ihsan A. 1973. “The Biosystematics of the Genus Thelypodium (Cruciferae).” Contributions from the Gray Herbarium of Harvard University, no. 204 (1973): 3-148. This authoritative (145-page) reference on Thelypodium can be viewed page-by-page on JSTOR at http://www.jstor.org/stable/41764710 or downloaded as part of a larger PDF containing Nos. 203, 204, and 205 from the Biodiversity Heritage Library at https://www.biodiversitylibrary.org/item/122971#page/154/mode/1up.

Nelson, Aven 1911. “New Plants from Idaho.” Botanical Gazette 52, no. 4 (Oct., 1911): 261-274. PDF available at: https://doi.org/10.1086/330635.

Payson, Edwin B. 1922. “A Monographic Study of Thelypodium and Its Immediate Allies.” Annals of the Missouri Botanical Garden, Vol. 9, No. 3 (Sep., 1922), pp. 233-324. A half-century earlier study than Al-Shehbaz, but still relevant. A complete PDF is available from JSTOR at https://www.jstor.org/stable/2990054.

Copyright © Tim Messick 2018. All rights reserved.

The Center of Diversity for Boechera

Did you know that Mono County is home to more species of Boechera (“rock-cress,” in the mustard family) than any other county in the United States?

Boechera retrofracta

Boechera puberula north of Masonic.

Neither did I, until I ran across a web page with 103 maps showing the number of species per county for the “Largest Genera in Continental North America”. This analysis is part of the Biota of North America Program (BONAP) (Kartesz 2015a, 2015b). The overall distribution patterns these maps reveal are interesting, and perusing the maps for familiar genera and favorite places is also enlightening. For example:

Inyo County, CA boasts the greatest diversity of Eriogonum (55 spp.), Phacelia (43 spp.), Lupinus (40 species), Cryptantha (24 spp.), and Ericameria (24 spp.).
San Bernardino County, CA has the greatest variety of Mentselia (24 spp.), Gilia (23 spp.), and Galium (20 spp.).
Garfield County, UT has the greatest numbers of Astragalus (59 spp.), Penstemon (31 spp.), Oreocarya (16 spp.), and Cymopterus (11 spp.).
Juncus is most diverse in Plumas County, CA (33 spp.).
Castilleja is most diverse in Fresno County, CA (21 spp.).
Artemisia is most diverse in Fremont County, WY (18 spp.) and nearly as diverse in Elko  County, NV.
Calochortus is most diverse in Kern County, CA (17 spp.).
And so on. As one might expect, the larger and more physiographically diverse counties are favored to have high numbers of species for large genera in the arid western states (e.g., Inyo, San Bernardino, Nye, and Coconino Counties). Perhaps grouping some adjacent small counties together would shift the locations of some hot spots.

Boechera retrofracta

Boechera puberula up close.

Mono County, then, is the center of diversity for Boechera, with 36 species (listed below). Sixteen of these are known or appear likely to occur in the Bodie Hills. No wonder I didn’t find them all during my field work 30-some years ago, and no wonder I gave up trying to key all my specimens and shipped them off to Reed C. Rollins (1911–1998), a professor of botany at Harvard University, and the renowned expert on many Cruciferae, including what we then called Arabis. He kindly annotated them all and shortly thereafter cited several of my specimens in describing Arabis bodiensis (now Boechera bodiensis) as a new species from material previously identified as Arabis fernaldiana var. stylosa. Rollins (1982) wrote, “Furthermore, an extensive sampling of Arabis populations of the Bodie Hills by Tim Messick has shown that what we name A. bodiensis below is consistent in its characters and is present on many appropriate sites throughout the area. This adds up to the necessity of recognizing the Bodie Hills material as an undescribed species.”

Boechera sp.

Boechera sp.at Grover Hot Springs in Alpine County.

The rock cress species are fairly challenging to identify. One often needs flowers (for their color), leaves (for their shapes and trichomes or hairs), intact fruits, and mature seeds to run a specimen successfully through the keys. Most Boechera plants don’t provide all of these parts in good condition all at the same time. One may need to key the same population in both spring and summer (taking notes and photographs) to do the job well. Familiarity and practice make for easier and more reliable identifications in any large group of plants, so the key to getting good with Boechera may be to live in or near Mono County.  Or Inyo County, which has nearly as many Boechera species.

Boechera sp.

Boechera sp. at Travertine Hot Springs

And finally, the elephant in the room is of course: How does one pronounce the name Boechera?  “BOH-chera” (long O) appears likely or even obvious to most Americans, but “oe” in Latin names is always pronounced “ee” (long E), as it should be in Oenothera or Oenanthe. So is it BEE-chera? Boechera is named for Tyge W. Boecher (1909–1983), a Danish botanist, evolutionary biologist, plant ecologist, and phytogeographer. But the Danish spelling is Böcher (with an o-umlaut), and this would suggest the “oe” (or ö) should be pronounced more like the “oe” in the French words oeil (eye) and oeuvre (an artist’s collected works). This sound can’t be spelled in English, but “BUH-chera,” with a listless enunciation of the first syllable, comes close. Or maybe “BOO-chera.” Take your pick.

Boechera sp.

Boechera sp. in Bridgeport Canyon. These are not especially showy plants.

The 36 species of Boechera in Mono County (according to CalFlora) are listed below. Those known or likely to be in the Bodie Hills are followed by a “(BH)”.

  1. Boechera arcuata (BH)
  2. Boechera bodiensis (BH)
  3. Boechera cobrensis (BH)
  4. Boechera covillei
  5. Boechera davidsonii
  6. Boechera depauperata
  7. Boechera dispar
  8. Boechera divaricarpa
  9. Boechera elkoensis (BH)
  10. Boechera evadens (BH)
  11. Boechera glaucovalvula
  12. Boechera howellii
  13. Boechera inyoensis
  14. Boechera lemmonii (BH)
  15. Boechera lyallii (BH)
  16. Boechera microphylla
  17. Boechera pauciflora (BH)
  18. Boechera paupercula (BH)
  19. Boechera pendulina
  20. Boechera pendulocarpa (BH)
  21. Boechera perennans
  22. Boechera pinetorum
  23. Boechera pinzliae
  24. Boechera platysperma (BH)
  25. Boechera puberula (BH)
  26. Boechera pulchra (BH)
  27. Boechera rectissima
  28. Boechera repanda
  29. Boechera retrofracta (BH)
  30. Boechera shockleyi
  31. Boechera sparsiflora (BH)
  32. Boechera stricta (BH)
  33. Boechera suffrutescens
  34. Boechera tiehmii
  35. Boechera tularensis
  36. Boechera xylopoda


Kartesz, J.T., The Biota of North America Program (BONAP). 2015a. North American Plant Atlas. (http://bonap.net/napa). Chapel Hill, N.C.

Kartesz, J.T. 2015b. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP) [maps]

Rollins, Reed C. 1982. Studies on Arabis (Cruciferae) of Western North America II. Contributions from the Gray Herbarium. 212: 103-114

Boechera sp. with Puccinia rust

Boechera becomes infected with the yellow, flower-mimicing Puccinia rust. (See the Puccinia post.)

Copyright © Tim Messick 2016. All rights reserved.