Plant Species of the San Jacinto Mountains
Funastrum crispum, wavyleaf twinevine

Jordan Zylstra and Tom Chester

Fig. 1. Funastrum crispum from the Cactus Spring Trail in Pinyon Flat. Note the "crisped" (wavy) margins on the leaves; the drooping greenish flowers; and the very large fruit. The leaves are typically grayish-green when fresh, but turn a darker color when the plant is fruiting.

Top and bottom left photos by Jordan Zylstra, from 5 June 2009. Bottom right photo by Don Rideout, from 2 September 2022.

Click on Jordan's pix for larger versions; click on Don's pix to go to his iNaturalist observation containing that photo.


Funastrum crispum (= Sarcostemma crispum) was unknown from California until 9 June 2009, when Jordan Zylstra was "poking around the SEINet website" on Sarcostemma species, and realized that F. crispum looked "exactly like the Pinyon Flat Sarcostemma!"

Jordan and Tom had puzzled over these Pinyon Flat plants for a full year. Those plants have a green corolla and large crisped dark green leaves unlike any Sarcostemma or Matelea we'd ever seen. However, since S. cynanchoides had been reported to have a green corolla in Utah and Arizona, and the anther head is free of the corolla ring, the only possible species match, for species known in California, was F. cynanchoides. But we were never happy with that identification, since the Pinyon Flat plants were so different from every other plant of F. cynanchoides.

Once F. crispum came into play, it turned out to be a perfect match for the Pinyon Flat plants. There were five characteristics given in the new Flora of Arizona key to separate these two species, and all five clearly went to F. crispum.

F. crispum was also a much better match for the 4000 foot elevation of Pinyon Flat, being found at 4000 to 6000 feet in Arizona. Munz 1974 only gave F. cynanchoides below 2000 feet elevation, although there are now vouchers up to 3000 feet in the San Jacinto / Santa Rosa Mountains, with a single voucher at the Dolomite Mine growing in limestone, an unusual rock type for this area, at 4000 feet.

Jordan had taken a voucher days earlier, on 27 May 2009. Once he discovered the correct species name, he put them in three herbaria (RSA, UCR, CAS), and alerted the Jepson Manual author Tom Rosatti about the find. Rosatti added F. crispum to the 2012 Second Edition of the Jepson Manual.

Tom looked at voucher distributions of Funastrum to see if there were any other high elevation vouchers in California that might be F. crispum, and found only a single high-elevation voucher of F. cynanchoides, from the Granite Mountains at 4500 feet.

We immediately alerted Jim Andre and Tasha La Doux about this find, to see whether it was actually F. crispum. Jim replied "I am familiar with this plant from Arizona, and I have not seen it in California, nothing even close."

This makes Pinyon Flat the only known location of F. crispum in California. This is unusual, since many Arizona species found in the San Jacinto / Santa Rosa Mountains are also found in the Mojave Preserve, as well as in Joshua Tree National Park.

For a number of years, we only knew of about one hundred plants in the population, primarily from a Forest Service survey done in 2006 for a firebreak around the populated area of the community of Pinyon Flat.

In 2014, Duncan Bell discovered a population of four large plants at a single location in a drainage on the east side of Horsethief Creek.

In late 2022, Bruce Watts did a survey for the plants in the Pinyon Flat area. This was an optimal time to survey for them, after a very good monsoonal rain season. He found a total of over 700 plants! See his survey results.

The full geographic distribution of F. crispum, from vouchers plotted by SEINet, is shown in Fig. 1.

Fig. 1. The geographic distribution of F. crispum, from vouchers plotted by SEINet on 15 December 2022. See also Interactive Voucher Map from SEINet

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Copyright © 2022 by Jordan Zylstra and Tom Chester.
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Comments and feedback: Tom Chester
Updated 15 December 2022.