Plant Species of San Jacinto Mountain: Bistorta bistortoides, western bistort
Table of Contents
Introduction
Geographic Distribution
Basal Leaves, and Discriminating Bistorta from Rumex
Possible Seedling
Taxonomic Notes
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| Fig. 1. Photos of the inflorescence of Bistorta bistortoides in bud (top left); full bloom (top center); and in fruit (top right). Bottom: a small field of Bistort flower heads visible within other meadow vegetation. Click on the photos for larger versions. | ||||
Introduction
Western bistort, Bistorta bistortoides, should have a much cuter name to go along with its charming flowers; see Fig. 1. It is a treasure to see its densely-flowered ~3 cm (1 inch) long heads poking through the surrounding vegetation. But the common and scientific name for this species comes from the twisted appearance of the root, bis ("twice") + torta ("twisted")!
On the other hand, the bistort flower head is quite similar to that of a number of other species in its family, so there is nothing really distinctive about the flower head to give it a good name.
"Western" bistort is aptly named because it is widespread throughout the western U.S.; see the range map at the bottom of the Southwest Colorado Wildflowers page on it. That page states that in the southwest Colorado region, western bistort is "abundant in high mountain and alpine areas, sometimes being so thick that it gives a snowy appearance to meadows". See that page for some excellent photos of this species in Colorado.
Unfortunately, Western bistort is not commonly seen at San Jacinto Mountain, being found in only nine locations that are almost entirely in or near boggy high-elevation locations that are off-trail. There are just 15 voucher collection events at San Jacinto Mountain, with nine of those collection events taken in 1892 to 1928. There are 30 iNat observations posted by 16 different observers as of 7 September 2024.
The low abundance of this species here is probably because San Jacinto Mountain is the southwestern edge of its geographical distribution. It is only found in one other location in all of southern California, the San Bernardino Mountains, where it is found in about eight locations. It is seen by iNat observers even less frequently there, with just four iNat observations of this species posted by four different observers.
Geographic Distribution
There are only nine locations at San Jacinto Mountain where B. bistortoides is found; see Table 1 and Figures 2 and 3. Most of our plants are found in Skunk Cabbage Meadow, Round Valley Meadow, and the uppermost part of Willow Creek below Wellman Cienega. There are probably significantly fewer than 1000 plants total of this species at San Jacinto Mountain. Our plants occur between elevations of 7700 and 9050 feet (2350 and 2750 m), with a median elevation of 8000 feet (2400 m). We surveyed the length of Tahquitz and Willow Creeks in 2009, finding B. bistortoides only in three of the 15 sections of our survey.
Table 1. Locations of B. bistortoides at San Jacinto Mountain, with estimated abundances
| Location | Minimum # of plants |
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| Skunk Cabbage Meadow | 100 |
| Round Valley Meadow | 50 |
| Uppermost part of Willow Creek below Wellman Cienega | 50 |
| Meadowy Area above 7 Pines Trail | 40 |
| Reeds Meadow | 25 |
| Candy's Creek | 10 |
| Tahquitz Meadow Area | 10 |
| Willow Creek | 1 |
| Long Valley Creek below Round Valley Meadow | 1 |
In addition, there is a 1928 voucher with locality of "Deer Springs". However, we suspect that voucher was actually from the "Meadowy Area above 7 Pines Trail", which is very nearby. Neither we nor anyone else has ever spotted B. bistortoides in the Deer Springs Campground area.
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| Fig. 2. All known locations at San Jacinto Mountain of B. bistortoides shown in a single map. Left: Topo Map. Right: Google Earth Map. See Fig. 3 for more detailed views of these locations. | |
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| Fig. 3. More detailed maps showing all known locations at San Jacinto Mountain of B. bistortoides in three separate maps. We have placed a question mark next to the blue diamond for the Deer Springs Campground location; see the text. | ||||
These locations are almost entirely from our surveys, including surveys done by Tom and other colleagues, 37 locations.
There are 15 voucher collection events at San Jacinto Mountain, but voucher locations are in general too imprecise to map accurately. Most have a quoted coordinate uncertainty of 1 to 10 km. There are only two vouchers with coordinates given to the five decimal digits that are needed for accurate plotting. One of those has coordinates that are about 0.2 miles away from the stated locality of "Round Valley Meadow", and thus was not used. The only voucher with a precise enough location was from M. Nazaire. It matches the location of an iNat observation, confirming its accuracy. We used one additional voucher from Mike Hamilton (not in the CCH1 or CCH2) from "Wellman Cabin", since we observed at least five locations in that nearby portion of Willow Creek.
We have used 21 iNat observations, 10 of which are from observations on our surveys and are included in our 37 locations reported above. The other 11 match well with our observations and the M. Nazaire voucher location. Six iNat observations were rejected as having imprecise locations. Some of those were of plants at a known location, but were mislocated by a small significant difference. Some of those were from observers that did not use a GPS or phone location to geolocate their photos, with their observations being located in areas where it was unlikely that B. bistortoides would be found.
Basal Leaves, and Discriminating Bistorta from Rumex
Most of the time that B. bistortoides is spotted at San Jacinto Mountain it only has basal leaves present. Worse, all the plants in a given spot may just have basal leaves, with no flowers in sight. This may be because the surrounding plants have shaded the leaves so much that the plant can't produce enough energy to bloom. It is also possible that the plants need to store energy from several years before they bloom. Or, because our area is at the very edge of the geographic range for B. bistortoides, perhaps the plants here just aren't very happy, and only bloom when they are found in an especially favorable place for them here. For example, note all the non-blooming rosettes in this iNat observation, accompanied by only a single blooming plant, despite the rosettes all being in a fairly open and sunny area.
The lack of a blooming plant nearby makes it difficult to be sure about the identification of the plant, since the basal leaves of B. bistortoides are similar to those of Rumex salicifolius, and to non-native Rumex species.
This page was in fact stimulated because Tom wanted to answer the question about how reliably one could identify the leaves of B. bistortoides if they weren't accompanied by a flower.
Fig. 4 shows some of the basal leaves of B. bistortoides.
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| Fig. 4. Basal leaves of B. bistortoides. Only the plant at lower right has a flower stalk. Click on the photos for larger versions. | ||||
Fortunately, in the higher elevations of San Jacinto Mountain where B. bistortoides grows, the only leaves that are similar are from Rumex salicifolius. Fig. 5 shows two examples of its leaves.
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| Fig. 5. Leaves of Rumex salicifolius from the higher elevations of San Jacinto Mountain. The plant shown on the left was growing next to mature seeding plants of R. salicifolius. The plant shown on the right was a flowering plant. Click on the photos for larger versions. | |
Three characteristics help to discriminate B. bistortoides and R. salicifolius plants that have only basal leaves:
- R. salicifolius is almost never observed as a rosette at San Jacinto Mountain. The example on the left in Fig. 5 was the only example Tom could find in his pix or in San Jacinto Mountain iNat posts. The rest of the time when we see R. salicifolius it is either in bloom or in fruit. It must develop beyond the basal leaf stage early in the growing season.
- Although the leaf of R. salicifolius can strongly resemble the leaf of B. bistortoides, it appears to have more prominent secondary veins, which are curved toward the tip of the leaf. It is hard to see any secondary veins in the leaves of B. bistortoides on the top of the leaf.
- The geographic distribution of these two species at San Jacinto Mountain has almost no overlap; see Fig. 6. B. bistortoides grows in meadows and meadow-like habitats, where R. salicifolius grows only in our creeks. The only place where they come close geographically is for the few plants of B. bistortoides that are found in meadow-like habitats in a few places in Willow Creek, which otherwise only has R. salicifolius.
Knowing that there is almost no overlap in the geographic distributions of these two species, and that R. salicifolius is only very rarely observed with only basal leaves present, gives one high confidence that if one observes basal leaves like those shown in Fig. 4, and one is in a meadowy habitat, those basal leaves are of B. bistortoides.
Fig. 6. Google Earth map of locations of B. bistortoides (pink filled circles) and Rumex salicifolius (light green filled circles). The locations of the two species are well separated except for the two locations of B. bistortiodes found in Willow Creek, which otherwise has only locations of R. salicifolius.
Possible Seedling
On 30 October 2011, Dave spotted a single seedling in a boggy part of Tahquitz Meadow that might be a seedling of B. bistortoides. Fig. 7 shows that seedling.
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| Fig. 7. A possible seedling of B. bistortoides. Note the asymmetric midvein. We think the light-brown structure on the stem below the cotyledons is the seed shell. Click on the photos for larger versions. | |
The cotyledons are somewhat reminiscent of those of Pedicularis semibarbata, but they aren't good matches to it, and we've never seen P. semibarbata growing in a boggy area. Compare to this P. semibarbata seedling and this one.
The seed shell on this seedling looks much like the seeds of B. bistortoides. Note the match with the overall shape, the brownish ridge along the edges that remained intact, and the acuminate tip.
The cotyledons have a lighter yellowish area at their base, matching the yellowish midvein of the true leaves of B. bistortoides.
We've posted this seedling at iNat. Maybe someone there can confirm or deny this determination.
Taxonomic Notes
The type specimen for this species was collected by Meriwether Lewis (of Lewis and Clark) in Idaho in 1806 and it was named Polygonum bistortoides by Pursh in his 1814 Flora Americae Septentrionalis. That scientific name translates as a Polygonum that resembles a Bistorta. Small decided in 1906 that it should be placed within the Bistorta genus, and transferred it there in Bull. Torrey Bot. Club 33: 57. Hence its funny name of a "bistort that looks like a bistort". (;-)
The Jepson eFlora distinguishes the two genera as follows:
8. Leaves generally basal; inflorescence terminal, spike-like; stems not branched ..... BISTORTA8' Leaves cauline; inflorescence terminal, axillary, spike-like or not; stems generally branched ====> POLYGONUM