Thymophylla pentachaeta var. belenidium
five-needled thymophylla

Fig. 1. Left: bud, showing the glands on the phyllaries and the hairs on the edges of the phyllaries. Right: Flower. Pictures taken by Tom Chester on 11 January 2014 in Smuggler Canyon. Click on the pictures for larger versions.

There has just been a single recorded observation of this species in San Diego County, a 2 January 1936 voucher from Frank Gander.

I and colleagues have been trying to relocate this species for several years. We first searched for this species in the vicinity of the reported location of Southeast slope of Pinyon Mt. without success.

After we visited the Calliandra location in Smuggler Canyon discovered by Franz Boshiero in 2005, it suddenly struck me that this Calliandra location might well be the Pinyon Mt. location of Gander et al that was from that same collection event in 1936 as the Thymophylla. Investigation by myself and James Dillane quickly revealed that was almost surely the case. So we'd been searching for Thymophylla in "all the wrong places"!

On 7 January 2014, Keir Morse decided to go up a tributary drainage to Smuggler Canyon that we hadn't previously surveyed, and then he went where his feet took him. He went up that drainage to a ridgeline, and then back down the ridgeline to the top of the impressive dry waterfall. On the way up, he discovered a new location of Carlowrightia arizonica, and on the way down he found Thymophylla.

What a day Keir had!

After 78 years and 5 days, we now possibly know where Gander took his voucher! (To be sure about Gander's location, we need more surveys to find out whether it exists in other places in this area.)

The route Keir explored is shown as the heavy red line in Fig. 2 (see also route shown on Google Earth).

Fig. 2. The heavy red line shows the route Keir Morse surveyed on 7 January 2014, with locations of interesting species marked. The dotted red lines show previous surveys in this area. Click on the figure for a version showing a larger area.

Keir reported that the Thymophylla plants were about six inches tall and very different from everything else. There were four plants in this area. Keir's photos of these plants are given in Fig. 3, reproduced here with permission from Keir. Compare them to the online picture of the Gander voucher.

Fig. 3. Left: Habit photograph. Right: Closeup of the heads in seed. Pictures taken by Keir Morse on 7 January 2014. Click on the pictures for larger versions.

 


 

On 11 January 2014, Adrienne Ballwey, myself, Kate Harper, Keir Morse and Jim Roberts headed to Keir's Thymophylla location to survey for more plants. On the way up, about a tenth of a mile before getting to Keir's location, I encountered a single population of seven plants. I was delighted that one of them still had some blooms left, and others were in seed! Pictures of those plants are given in Figs. 4 and 5.

The name pentachaeta means five scales, which is the source of the common name five-needled. However, the pappus on the seeds is said to consist of ten scales, not five, each dissected into three awn-like tips. The original description (as Hymenatherum pentachaetum) says pappi squamellis 5 basi submembranaceis subtrifidis. Although I can't translate that for sure, it sounds like the original author thought there were only five scales, each dissected into three awn-like tips. In Fig. 4, the number of scales looks closer to five than ten. We'll return to photograph a single fruit to get an accurate count of the scales.

Fig. 4. Left: Flower with thumb for scale. Right: Closeup of the seeds. Pictures taken by Tom Chester on 11 January 2014. Click on the pictures for larger versions.

Fig. 5. Left: Plant with mm ruler for scale. The bloom shown on the right is at upper left in this picture. Right: Flower with mm ruler for scale. Pictures taken by Kate Harper on 11 January 2014. Click on the pictures for larger versions.

 


 

The difficulty of searching for Thymophylla in this area is seen in the full camera frame shown in Fig. 6. Keir's Thymophylla location is just below the big boulders in the immediate foreground. Those boulders help give Keir's Thymophylla location extra water.

Fig. 6. Single camera frame taken toward the northwest from just above Keir's Thymophylla location. Note Kate Harper in the picture for scale. Picture taken by Tom Chester on 11 January 2014. Click on the picture for a larger version.

The location I found also had extra water, although it wasn't immediately apparent by looking at the vicinity of the plants. But Jim Roberts spotted a Hyptis emoryi, desert lavender, nearby, indicating that the location of my plants was significantly wetter than other nearby areas.

These two locations are not directly at the base of the big boulders, but are in flattish areas a bit away from them that must get extra runoff from the big boulders uphill, either above or below ground.

In Fig. 6, Thymophylla could be just downhill from almost any of the numerous large boulders visible in the picture. But it is a daunting, and very slow, task to search all those areas!


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Copyright © 2014 by Tom Chester.
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Comments and feedback: Tom Chester
Updated 14 January 2014