Plants of Southern California: Potentilla glandulosa subspecies

Drymocallis glandulosa var. wrangelliana
formerly part of Potentilla glandulosa ssp. glandulosa
© Michael Charters, Santa Rosa Plateau, Santa Ana Mountains, 2000 feet (610 m) elevation
Drymocallis lactea var. lactea
formerly Potentilla glandulosa ssp. nevadensis
© Michael Charters, Wellman Cienega, San Jacinto Mountains, 9000 feet (2750 m) elevation
Drymocallis glandulosa var. viscida
formerly part of Potentilla glandulosa ssp. reflexa
© Tom Chester, Marion Mountain trail, San Jacinto Mountains, 8050 feet (2450 m) elevation. (more pix and analysis)
Drymocallis glandulosa var. reflexa
formerly part of Potentilla glandulosa ssp. reflexa
© Michael Charters, Horse Meadow, San Bernardino Mountains, 7360 feet (2240 m) elevation (more pix and analysis)


Table of Contents

Introduction
Taxonomic Changes in the Jepson Manual Second Edition Treatment
    Taxa in southern California
    San Jacinto Mountains and Riverside County Taxa (key, detailed characteristics, range maps)
Data
Analysis


Introduction

Sometimes progress is achieved by resurrecting wisdom from the distant past. That's what Barbara Ertter has done in the second edition Jepson Manual treatment by restoring a taxon that had been lost, ignored or subsumed into other taxa for roughly one hundred years. My preliminary take is that this brilliant move has given the correct name for the dominant taxon from the Potentilla glandulosa group in the Pine Belt of the San Jacinto Mountains (SnJt), and has possibly resolved several problems I have had in determining those plants.

In the Pine Belt of SnJt, using the taxonomy of the first edition Jepson Manual treatment, we have two subspecies of P. glandulosa, ssp. reflexa and ssp. nevadensis. In the past, I have primarily relied on the color and width of the petals to separate ssp. reflexa from ssp. nevadensis at SnJt in the elevation ranges where they overlap. Above that elevation I've taken the plants to be entirely ssp. nevadensis, and below that elevation to be entirely ssp. reflexa. But I have never done careful full determinations on these plants, analysis on how well these two taxa separate here, nor compiled my data to understand better the geographic separation.

Although I've certainly done my share of puzzling over how some plants fit the Jepson Manual key, most specimens seemed to sort out into one subspecies or another. The only real puzzlement I've had is in the variation in the color of the petals for the plants at the higher elevations in SnJt that appear to be ssp. nevadensis, which range from white to yellow. The Jepson Manual treatment says the petals are cream, which doesn't seem to fit the plants with yellow petals.

On 3 July 2010, Michael Charters posted a field gallery from the Heaps Peak Arboretum showing a P. glandulosa that he called ssp. reflexa that had white / cream colored petals and appeared to be fairly wide. I raised a question about the determination of those plants, since ssp. reflexa was supposed to have narrow yellow petals. They appeared to be ssp. glandulosa, even though the elevation of Heaps Peak Arboretum is 6000 feet (1800 m), and the Jepson Manual said ssp. glandulosa was gen < 1200 m.

I then became curious as to how well ssp. nevadensis separates from ssp. reflexa at SnJt morphologically and geographically, as well as how they separate from ssp. glandulosa. On 6 July 2010, I began to study this question by photographing and measuring plants in four distinct locations at SnJt that I encountered on a botanical trip on the Marion Mountain Trail and an earlier stop at Idyllwild Park.

Coincidentally, at about the same time, Michael Charters was curious about the subspecies determinations for a number of plants he had photographed from SnJt and the San Bernardino Mountains (SnBr), and sent me those pictures.

Michael also told me about the second edition Jepson Manual treatment that was now online. Ertter's new treatment turned out to be critical in resolving my puzzlement. Interestingly, the taxon she restored has features that are intermediate between ssp. nevadensis and ssp. reflexa. It thus appears that some of my previous determinations, and probably those of a number of vouchers, actually correspond to Ertter's restored taxon.

This article first reviews the taxonomic changes of all the P. glandulosa subspecies as they appear in the second edition Jepson Manual treatment, emphasizing the changes for the southern California taxa. It then presents the data I've begun to collect on the SnJt plants. Analysis of those data will be presented in the future when I've collected enough data.

Taxonomic Changes in the Jepson Manual Second Edition Treatment

In the draft Jepson Manual Second Edition Treatment for Rosaceae, all subspecies of Potentilla glandulosa in the First Edition have been moved to Drymocallis. The basis for resurrecting that older name is that P. glandulosa, and two similar species not found in California, are now recognized as being closely related to Fragaria. The other Potentilla species are more closely related to Horkelia and Ivesia.

The botanical rules for names require that all species under the same genus name share the same evolutionary history. With this new understanding, P. glandulosa would have to be moved to Fragaria; Fragaria would have to be included under an expanded Potentilla; or P. glandulosa would have to be moved to a separate genus. The least disruptive course is the latter, since these taxa had mostly been treated under the Drymocallis genus in 1898. See Generic Realignments In tribe Potentileae and revision of Drymocallis (Rosoideae : Rosaceae ) in North America by Barbara Ertter, J. Bot. Res. Inst. Texas 1(1): 31 - 46, 2007, for a much more complete discussion of this problem.

The eight subspecies of P. glandulosa in the 1993 Jepson Manual have now become 12 taxa in six species, and, due to the splitting, D. glandulosa var. glandulosa, which contains many of the plants called P. glandulosa ssp. glandulosa, no longer occurs in southern California!

The subspecies of P. glandulosa that have been split, along with their Second Edition Jepson Manual southern California geographic distribution are:

The new synonymy is:

First Edition NameSecond Edition Name (CA distribution for split taxa)
Potentilla glandulosa ssp. ashlandica Drymocallis lactea var. austiniae
Potentilla glandulosa ssp. ewanii Drymocallis cuneifolia var. ewanii
Potentilla glandulosa ssp. glandulosa* Drymocallis glandulosa var. glandulosa (KR, NCoR, CaR, SN, ScV (Sutter Buttes), MP)
Drymocallis glandulosa var. wrangelliana* (NCo, NCoRO, CW, SCo)
Potentilla glandulosa ssp. globosa Drymocallis rhomboidea
Potentilla glandulosa ssp. hanseni Drymocallis hansenii
Potentilla glandulosa ssp. nevadensis+ Drymocallis cuneifolia var. cuneifolia (SnBr n of Big Bear Lake = former P. peirsonii)
Drymocallis lactea var. lactea (others)
Potentilla glandulosa ssp. pseudorupestris Drymocallis pseudorupestris var. crumiana
Drymocallis pseudorupestris var. saxicola
Potentilla glandulosa ssp. reflexa Drymocallis glandulosa var. reflexa (KR, NCoRH, CaRH, SNH, SnGb, SnBr, PR)
Drymocallis glandulosa var. viscida (TR, PR)
* Some southern California specimens previously determined as P. glandulosa ssp. glandulosa are actually D. glandulosa var. viscida if the second edition Jepson Manual treatment is correct that D. glandulosa var. wrangelliana is confined to the SCo in southern California. Alternatively, if those vouchers are actually D. glandulosa var. wrangelliana, the distribution must include TR, PR, and extend up to 6000 feet elevation or higher. This seems likely from the pictures of Michael Charters.

+ Some specimens previously determined as P. glandulosa ssp. nevadensis may actually be D. glandulosa var. viscida, since this resurrected taxon "combines the flower and vestiture of Drymocallis glandulosa var. reflexa with the narrow inflorescence and predominately single-toothed leaflets of D. lactea var. lactea" (Ertter 2007).

Taxa in southern California

The Drymocallis taxa that are in southern California are:

TaxonSouthern California distribution
Drymocallis cuneifolia var. cuneifoliaSnBr (n of Big Bear Lake)
Drymocallis cuneifolia var. ewaniiSnGb (Mount Islip area)
Drymocallis glandulosa var. reflexaSnGb, SnBr, PR
Drymocallis glandulosa var. viscidaTR, PR
Drymocallis glandulosa var. wrangellianaSCo*
Drymocallis lactea var. lacteaTR, SnJt
* It is possible that the distribution should include TR, PR if the southern California specimens previously determined as P. glandulosa ssp. glandulosa are actually D. glandulosa var. wrangelliana. It appears from the pictures of Michael Charters that this is indeed the case, with var. wrangelliana extending up to 6000 feet elevation at SnBr.

Due to the resurrection of D. glandulosa var. viscida, it is currently difficult to know which online vouchers of P. glandulosa ssp. reflexa are actually D. glandulosa var. reflexa, and which are actually D. var. viscida. The only vouchers that can be trusted right now are those determined by Ertter after she resurrectd var. viscida. The following table shows a summary of those Ertter vouchers:

Regionvar. reflexavar. viscida
SnGb56
SnBr26
SnJt16
Total818

It appears from the above that var. viscida is the dominant variety at SnBr and SnJt, whereas the two varieties might be equally abundant at SnGb.

Taxa in San Jacinto Mountains and Riverside County

For detailed information on the taxa found in the San Jacinto Mountains, as well as distribution maps in Riverside County along with elevation histograms, see Plant Species of San Jacinto Mountain: Potentilla glandulosa, sticky cinquefoil (Drymocallis glandulosa and D. lactea).

Data

San Jacinto Mountains, 6 July 2010

I will first consider the four populations I encountered on 6 July 2010 one by one. I'll eventually analyze these, and other populations, with Principal Components. For these four populations, I was not aware of the importance of the inflorescence branch angle, so I took no note of that.

On SR243 at Idyllwild Park, in Idyllwild, elevation 5600 feet (1707 m). Pictures: leaves; pedicel; and flower.

The pedicel and lower stem have a significant number of glandular hairs. The leaflet teeth are single to double, with perhaps somewhat more single teeth than double teeth, with 5-9 individual teeth per side (counting a "double tooth" as two teeth). The sepals are spreading, with acute tips having angles of 60-90°, and are 1.38 times the petal length on average. The petals are yellow and elliptic in shape. These clearly key to D. glandulosa, and probably to var. viscida.

Near the base of the Marion Mountain Trail, on the west side of the San Jacinto Mountains, northwest of Idyllwild, elevation 6800 feet (2070 m). Pictures: leaves; lower stem; and flower.

The lower stem is densely glandular hairy. The leaflet teeth are mostly single, with 4-9 individual teeth per side. The sepals are spreading, with acute tips having angles of 45-60°, and are 1.38 times the petal length on average. The petals are light yellow and obovate in shape. These appear to clearly key to D. glandulosa var. viscida.

Just below the midpoint of the Marion Mountain Trail, elevation 7100 feet (2160 m). Pictures: lower stem; leaves; pedicel; flower 1; flower 2; flower 3; and flower 4.

The lower stem and pedicels are densely glandular hairy. The leaflet teeth are about half single and half double, with 4-12 individual teeth per side. The sepals are reflexed, with acute tips having angles of 55-90°. The sepals are probably somewhat longer than the petals, but it is hard to tell from a photograph since the sepals are reflexed. The petals are light yellow, 5 x 1.5 mm, and oblong/ elliptic in shape, with the edges curled down. These appear to clearly key to D. glandulosa, but without knowing the branch angle, it is difficult to assign this to a variety. The acute tips of the sepals indicate var. viscida but the number of teeth indicates var. reflexa.

Near the top of the Marion Mountain Trail, below the junction with the PCT, elevation 8050 feet (2160 m). Pictures: leaves; pedicel; just opened flower 1; and flower 2.

The pedicels are densely glandular hairy. The leaflet teeth are mostly single, with 4-9 individual teeth per side. The sepals appear to be mostly spreading, but it is possible that the tips are somewhat reflexed. The sepals tips have angles of 55-75°. In the photograph I measured, the sepals are slightly shorter than the petals, but I suspect that is because the tips of the sepals are somewhat reflexed. The petals are light yellow, 4 x 3 mm, and elliptic / obovate in shape. These appear to also be D. glandulosa var. viscida.

San Bernardino Mountains, 11 July 2010

The pictures and data were all from Michael Charters.

Horse Meadow, elevation 7360 feet (2240 m). Pictures: stem base hairs; leaves 1; leaves 2; pedicel hairs; inflorescence branch angle 1; inflorescence branch angle 2; and flower.

The lower stem and pedicels are densely glandular hairy. The leaflet teeth are mostly double, with 8-13 per side. The inflorescence branch angle is measured in the photographs to be 32-42°, which is a minimum value. The sepals are spreading, with tips angles of 60-180°, with a median angle of 80°. The petals are shorter than the sepals, yellow, elliptic-obovate. Michael measured the petals to be 4.0-4.5 mm x 3.0 mm.

These plants appear to be clear D. glandulosa var. reflexa. The inflorescence branch angle strongly gives this determination. The number of leaflet teeth; the preponderance of double teeth; and the tendency toward "more obtuse" sepal tips also support this determination, even if most of the sepal tips are not actually obtuse.

Analysis

Not enough data has been accumulated for analysis yet.


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Copyright © 2010 by Tom Chester
Permission is freely granted to reproduce any or all of this page as long as credit is given to me at this source:
http://tchester.org/plants/analysis/potentilla/glandulosa_subspecies.html
Comments and feedback: Tom Chester
Last update: 11 July 2010