Flora of Clark Valley Area

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Introduction
Checklist

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Flora of Clark Valley Area

This checklist is a start at a flora of the Clark Valley Area. It consists of 157 taxa. Of those 157 taxa, we observed 121 in five different field surveys, and 110 of the 157 taxa have been vouchered here.

The checklist is current as of 11 February 2020, but the following text is from a previous version of this page done in the year 2008.

The floristic area denoted as the Clark Valley Area is delineated by the region outlined in red in the following map:

Only a single road traverses this area, the Rockhouse Canyon Road, on the western side of the Valley (see map below). There is also a private road that accesses private land on the north side of Clark Lake.

The western boundary of this area is the ridgeline / drainage divide of Coyote Mountain and its extension northward, to include the entire drainage basin of Butler Canyon / Rockhouse Canyon up to the San Diego County border with Riverside County.

The eastern boundary is mostly at the 3000 foot elevation contour of the Santa Rosa Mountains. The southeastern boundary is placed just a bit to the west of the Villager Peak Trail and Rattlesnake Canyon, since those two areas are more naturally included in the neighboring floristic area.

The southern boundary is set along Highway S22 to divide Clark Valley from the Badlands. Although this boundary is somewhat arbitrary, S22 gives a well-defined boundary.

For more information about Clark Valley, including pictures from our surveys, see Borrego Desert: Clark Valley.

Voucher Records

The voucher search was redone on 24 December 2016. This time only vouchers from Clark Valley itself and the immediately-surrounding areas were accepted. The following text has not been changed from the previous search.

The vouchers come from a search on 8 December 2008 of the Consortium of California Herbaria. The Consortium records were searched for San Diego County specimens that contained the word Clark in the locality (297 vouchers), as well as records with coordinates that fell within a rectangle that encompassed this area (369 vouchers). Duplicate vouchers, vouchers outside this area, and vouchers determined only to the genus that had more than one possible species, were removed.

This process yielded a total of 226 vouchers of 133 unique taxa.

The dominant collectors in the Consortium records were Larry Hendrickson and Kim Marsden and vice-versa, 83 vouchers; R. Mitchel Beauchamp, R. C. Pierce, 71 vouchers; and Bill Sullivan, 31 vouchers. These three sets of collectors accounted for 185 of the 226 vouchers, 82% of the total.

The locations of the vouchers are plotted in the following map, which also shows the boundaries of this region in more detail:

Because many vouchers share the same location, there are far fewer than 226 points plotted above.

Field Work

Field work has been added from 3/7/09, 12/19/09, and 12/27/16, but the following text has not yet been updated.

Three different areas within the Clark Valley area have been field surveyed. On 27 December 2007, James Dillane, Wayne Armstrong and I surveyed the 2.7 miles of the Alcoholic Pass Trail on Coyote Mountain that are on the Clark Valley side. We surveyed only for species not previously found on the southwestern side of the trail, so this survey was very incomplete. That portion of the trail is shown in green on the following map:

On 9 and 12 December 2008, Mike Crouse and I surveyed the two different routes shown in the following map :

We surveyed 5.75 unique miles on 9 December 2008, and 5.7 unique miles on 12 December 2008.

We also scanned the slopes of the nearby portion of the Santa Rosa Mountains for the elephant trees, Bursera microphylla, reported from that location (indicated by the labeled line in the above map), without finding them. However, since those trees were likely to be leafless at that time, they easily could have escaped our binocular survey from afar. This species was added to the checklist below based on sightings by Mark Jorgensen and Larry Hendrickson.

Note added 30 December 2016: We relocated the elephant trees on 19 December 2009 and vouchered one of them; see The Elephant Trees of Clark Valley.

A total of 63 taxa that could be fairly-confidently identified were found in those three December searches; 19 of those 63 taxa, 30%, are not among the vouchered species. A small number of additional taxa were found that could not be confidently identified at those times.

The unvouchered species do not come from any general problem with my identifications, since those unvouchered species include such easy-to-recognize taxa as Opuntia ramosissima, Psorothamnus spinosus, Ferocactus cylindraceus, and Encelia farinosa. This simply reflects the lack of botanical work for this area. It is possible that one or two of the unvouchered species might be misdetermined, since some of those determinations were made from dead plants.

Total Checklist

The total number of taxa presented below is 153, 148 of which are native. Of the 153 taxa, 63 were observed on one of the three field surveys, leaving 90 to be found from surveys at a more optimal time of year, or in locations not yet surveyed. Since 30% of the observed taxa are so far unvouchered, this may imply that the voucher list is on the order of 30% incomplete. However, since many of the unvouchered taxa are common, it may only imply that the most common taxa have not yet been vouchered.

Another source of incompleteness for this checklist is that most of the area has never been surveyed, especially the steep lower slopes of the Santa Rosa Mountains which may defy further surveys indefinitely. I estimate at most 24 square miles (62 km²) has had any survey within it, whereas 34 square miles (88 km²) has never had any survey within it. Using the standard relationship that the number of species scales as the 0.3 power of the area, this implies that (58/24)^0.3 = 1.30 times more species should be found in the total area of ~58 square miles. This incompleteness is an additional factor to the incompleteness of the surveyed areas.

Thus the checklist below may be on the order of 1 / 1.3² ~ 60% complete, implying that the true number of taxa in this area might be roughly 260 instead of the 153 present below.

Checklist for the Clark Valley Area

This checklist is current as of 11 February 2020.

This checklist is only for a subset of the Clark Valley Floristic Area defined above, of just the floor of the Valley and the immediately-adjacent areas. Rockhouse Canyon / Butler Canyon has its own flora since that area is very different floristically from the desert floor area.

See:

• Notes on the Scientific Names Used At This Site and
• Information about the order in which the species are presented, and the links from the Scientific Name and Common Name.

An asterisk before the common name indicates a non-native species.

The column with header #Pls gives the minimum number of observed plants from all the surveys in this area, up to a maximum of 99 plants. An x indicates we have observed that taxon but no abundance estimate was made. A V in this column indicates a species that was vouchered in this area that we haven't yet seen. An iN in this column indicates a species with an iNat observation as of 11 February 2020 that we haven't seen and that hasn't been vouchered. A FC in this column indicates a species on Fred Melgert and Carla Hoegen's plant list for this area for 11 February 2020 that wasn't seen, vouchered, or at iNat.

One species, Helianthus niveus ssp. tephrodes, has nr in this column since it may or may not be present in this area, but has been vouchered near this area. One voucher from 1933 has a vague location of North Borrego Valley on road to Clark Lake. Another voucher is from just east of this area on S22.

Version for printing, without lines and other text on this page: html (5 pages) or pdf Clickbook booklet (2 double-sided pages). (See printing instructions for an explanation of these options)

#	Fam	Scientific Name	(*)Common Name	#Pls
Ferns
1	Pte	Cheilanthes parryi	woolly lipfern	10
Eudicots
2	Aca	Justicia californica	chuparosa	x
3	Ama	Amaranthus blitoides	*mat amaranth	20
4	Ama	Amaranthus fimbriatus	fringed amaranth	V
5	Ama	Tidestromia suffruticosa var. oblongifolia	Arizona honeysweet	15
6	Apo	Asclepias subulata	rush milkweed	2
7	Apo	Funastrum hirtellum	rambling milkweed	V
8	Apo	Pilostyles thurberi	Thurber's pilostyles	1
9	Ast	Ambrosia dumosa	burroweed	99
10	Ast	Ambrosia salsola var. salsola	cheesebush	5
11	Ast	Baileya pauciradiata	Colorado Desert marigold	79
12	Ast	Bebbia juncea var. aspera	sweetbush	4
13	Ast	Calycoseris parryi	yellow tackstem	V
14	Ast	Calycoseris wrightii	white tackstem	V
15	Ast	Chaenactis carphoclinia var. carphoclinia	pebble pincushion	V
16	Ast	Chaenactis fremontii	Fremont pincushion	20
17	Ast	Chaenactis stevioides	desert pincushion	99
18	Ast	Dicoria canescens	desert dicoria	20
19	Ast	Encelia farinosa	brittlebush	20
20	Ast	Encelia farinosa var. farinosa	brittlebush	iN
21	Ast	Encelia farinosa var. phenicodonta	purple disk flower brittlebush	iN
22	Ast	Encelia frutescens	button encelia	2
23	Ast	Geraea canescens	hairy desert-sunflower	99
24	Ast	Helianthus niveus ssp. tephrodes	Algodones Dunes sunflower	nr
25	Ast	Helianthus petiolaris ssp. canescens	gray desert sunflower	V
26	Ast	Isocoma acradenia var. acradenia	entire-leaved alkali goldenbush	V
27	Ast	Isocoma acradenia var. eremophila	toothed-leaved alkali goldenbush	99
28	Ast	Lactuca serriola	*prickly lettuce	FC
29	Ast	Lepidospartum squamatum	scale-broom	V
30	Ast	Logfia arizonica	Arizona herba impia	iN
31	Ast	Logfia depressa	dwarf filago	FC
32	Ast	Malacothrix glabrata	desert dandelion	30
33	Ast	Monoptilon bellioides	desert star	x
34	Ast	Palafoxia arida var. arida	Spanish needle	40
35	Ast	Pectis papposa var. papposa	chinch-weed	iN
36	Ast	Perityle emoryi	Emory's rock-daisy	V
37	Ast	Peucephyllum schottii	pygmy-cedar	x
38	Ast	Pluchea sericea	arrow-weed	99
39	Ast	Psathyrotes ramosissima	turtleback	x
40	Ast	Rafinesquia neomexicana	desert chicory	99
41	Ast	Senecio mohavensis	Mojave ragwort	iN
42	Ast	Stephanomeria exigua ssp. exigua	slender wreathplant	V
43	Ast	Stephanomeria pauciflora	wire-lettuce	1
44	Ast	Trichoptilium incisum	yellow-head	V
45	Ast	Trixis californica var. californica	California trixis	1
46	Ast	Volutaria tubuliflora	*Mediterranean desert knapweed	iN
47	Ast	Xylorhiza orcuttii	Orcutt's woody-aster	V
48	Big	Chilopsis linearis ssp. arcuata	desert-willow	V
49	Bor	Amsinckia intermedia	common fiddleneck	iN
50	Bor	Amsinckia tessellata var. tessellata	bristly fiddleneck	V
51	Bor	Cryptantha angustifolia	narrow-leaved cryptantha	99
52	Bor	Cryptantha barbigera var. barbigera	bearded cryptantha	1
53	Bor	Cryptantha barbigera var. fergusoniae	Santa Rosa Mountain bearded cryptantha	iN
54	Bor	Cryptantha costata	ribbed cryptantha	V
55	Bor	Cryptantha ganderi	Gander's cryptantha	x
56	Bor	Cryptantha maritima	Guadalupe cryptantha	5
57	Bor	Cryptantha micrantha var. micrantha	red-root cryptantha	V
58	Bor	Cryptantha nevadensis var. nevadensis	Nevada cryptantha	x
59	Bor	Cryptantha pterocarya	wing-nut cryptantha	x
60	Bor	Emmenanthe penduliflora var. penduliflora	whispering bells	iN
61	Bor	Eucrypta micrantha	desert eucrypta	iN
62	Bor	Heliotropium curassavicum var. oculatum	seaside heliotrope	x
63	Bor	Nama demissa var. demissa	purple mat	iN
64	Bor	Pectocarya heterocarpa	chuckwalla pectocarya	10
65	Bor	Pectocarya peninsularis	Baja pectocarya	V
66	Bor	Pectocarya platycarpa	broad-fruited combseed	1
67	Bor	Pectocarya recurvata	curvenut combseed	V
68	Bor	Phacelia crenulata var. ambigua	heliotrope phacelia	20
69	Bor	Phacelia crenulata var. minutiflora	little-flowered heliotrope phacelia	20
70	Bor	Phacelia distans	common phacelia	10
71	Bor	Phacelia ivesiana	Ives' phacelia	iN
72	Bor	Phacelia neglecta	alkali phacelia	iN
73	Bor	Plagiobothrys jonesii	Jones' popcorn flower	iN
74	Bor	Tiquilia palmeri	Palmer's coldenia	1
75	Bor	Tiquilia plicata	plicate coldenia	V
76	Bra	Brassica tournefortii	*Sahara mustard	99
77	Bra	Caulanthus lasiophyllus	California mustard	iN
78	Bra	Descurainia pinnata	western tansy-mustard	FC
79	Bra	Dithyrea californica	spectacle-pod	1
80	Bra	Draba cuneifolia	wedge-leaved draba	iN
81	Bra	Lepidium lasiocarpum ssp. lasiocarpum	hairy-podded pepper-grass	99
82	Bra	Sisymbrium irio	*London rocket	5
83	Bra	Streptanthella longirostris	longbeak streptanthella	5
84	Bra	Tropidocarpum gracile	slender tropidocarpum	iN
85	Bur	Bursera microphylla	elephant tree	13
86	Cac	Cylindropuntia bigelovii	teddy-bear cholla	x
87	Cac	Cylindropuntia echinocarpa	silver cholla	22
88	Cac	Cylindropuntia ganderi	Gander's cholla	15
89	Cac	Cylindropuntia ramosissima	pencil cholla	20
90	Cac	Echinocereus engelmannii	Engelmann's hedgehog cactus	1
91	Cac	Ferocactus cylindraceus	California barrel cactus	8
92	Cac	Mammillaria dioica	California fish-hook cactus	1
93	Cac	Opuntia basilaris var. basilaris	beavertail cactus	1
94	Cam	Nemacladus glanduliferus	glandular nemacladus	iN
95	Cam	Nemacladus orientalis	eastern glandular nemacladus	iN
96	Car	Achyronychia cooperi	frost mat	V
97	Che	Allenrolfea occidentalis	iodine-bush	99
98	Che	Atriplex canescens var. laciniata	Caleb four-wing saltbush	99
99	Che	Atriplex elegans var. fasciculata	wheelscale	10
100	Che	Atriplex hymenelytra	desert holly	3
101	Che	Atriplex lentiformis ssp. lentiformis	big saltbush	65
102	Che	Atriplex polycarpa	cattle saltbush	99
103	Che	Monolepis nuttalliana	Nuttall's poverty weed	99
104	Che	Salsola paulsenii	*Paulsen's Russian thistle	99
105	Che	Suaeda nigra	bush seepweed	99
106	Cle	Cleomella obtusifolia	Mojave cleomella	iN
107	Cle	Peritoma arborea	bladderpod	V
108	Cle	Wislizenia refracta ssp. palmeri	Palmer's jackass clover	V
109	Con	Cuscuta californica var. papillosa	papillate dodder	3
110	Cra	Crassula connata	pygmy-weed	FC
111	Cro	Crossosoma bigelovii	rock crossosoma	V
112	Eup	Chamaesyce micromera	Sonoran spurge	1
113	Eup	Chamaesyce polycarpa	small-seeded spurge	80
114	Eup	Chamaesyce setiloba	starfish (Yuma) spurge	V
115	Eup	Croton californicus	California croton	3
116	Eup	Ditaxis lanceolata	narrowleaf ditaxis	x
117	Eup	Ditaxis neomexicana	New Mexico ditaxis	V
118	Eup	Stillingia spinulosa	annual stillingia	20
119	Fab	Acmispon strigosus	strigose lotus	1
120	Fab	Astragalus crotalariae	Salton milk-vetch	99
121	Fab	Astragalus didymocarpus var. dispermus	dwarf white milk-vetch	V
122	Fab	Astragalus lentiginosus var. borreganus	Borrego milk-vetch	99
123	Fab	Dalea mollis	silky dalea	V
124	Fab	Dalea mollissima	downy dalea	x
125	Fab	Lupinus arizonicus	Arizona lupine	23
126	Fab	Lupinus shockleyi	desert lupine	iN
127	Fab	Parkinsonia florida	blue palo verde	iN
128	Fab	Prosopis glandulosa var. torreyana	honey mesquite	99
129	Fab	Psorothamnus emoryi	Emory's indigo-bush	15
130	Fab	Psorothamnus schottii	indigo bush	50
131	Fab	Psorothamnus spinosus	smoke tree	1
132	Fab	Senegalia greggii	catclaw	20
133	Fou	Fouquieria splendens ssp. splendens	ocotillo	8
134	Ger	Erodium cicutarium	*redstem filaree	10
135	Ger	Erodium texanum	Texas filaree	x
136	Kra	Krameria bicolor	white rhatany	40
137	Lam	Hyptis emoryi	desert-lavender	10
138	Lam	Salvia columbariae	chia	5
139	Lam	Salvia vaseyi	Vasey's sage	10
140	Loa	Mentzelia affinis	yellow blazing star	20
141	Loa	Mentzelia desertorum	desert blazing star	V
142	Loa	Mentzelia involucrata	bracted blazing star	3
143	Loa	Petalonyx thurberi ssp. thurberi	Thurber's sandpaper-plant	10
144	Mal	Eremalche exilis	white mallow	1
145	Mal	Eremalche rotundifolia	desert five-spot	V
146	Mal	Hibiscus denudatus	rock hibiscus	x
147	Mal	Malva parviflora	*cheeseweed	iN
148	Mal	Sphaeralcea angustifolia	copper globemallow	99
149	Mon	Calyptridium monandrum	sand cress	iN
150	Mon	Cistanthe ambigua	dead man's fingers	99
151	Nyc	Abronia villosa var. villosa	hairy sand-verbena	50
152	Nyc	Allionia incarnata var. incarnata	small-flowered trailing four o'clock	iN
153	Nyc	Boerhavia triquetra var. intermedia	fivewing spiderling	iN
154	Nyc	Mirabilis laevis var. retrorsa	Bigelow's desert four-o'clock	iN
155	Ona	Camissoniopsis pallida ssp. pallida	pale suncup	iN
156	Ona	Chylismia claviformis ssp. peirsonii	brown-eyed primrose	99
157	Ona	Eremothera boothii ssp. condensata	Booth's evening primrose	7
158	Ona	Eulobus californicus	California suncup	99
159	Ona	Oenothera deltoides ssp. deltoides	dune primrose	99
160	Oro	Orobanche cooperi	Cooper's broomrape	iN
161	Pap	Eschscholzia minutiflora ssp. minutiflora	small-flowered poppy	x
162	Pap	Eschscholzia parishii	Parish's poppy	x
163	Phr	Mimulus bigelovii var. bigelovii	Bigelow's monkeyflower	x
164	Pla	Mohavea confertiflora	ghost flower	V
165	Pla	Plantago ovata	desert plantain	99
166	Pol	Aliciella latifolia ssp. latifolia	broad-leaf gilia	x
167	Pol	Eriastrum eremicum ssp. eremicum	desert woolly-star	5
168	Pol	Eriastrum harwoodii	Harwood's woolly-star	iN
169	Pol	Gilia stellata	star gilia	iN
170	Pol	Langloisia setosissima ssp. setosissima	bristly langloisia	iN
171	Pol	Linanthus jonesii	Jones' linanthus	iN
172	Pol	Loeseliastrum matthewsii	desert calico	V
173	Pol	Loeseliastrum schottii	Schott's calico	99
174	Pol	Chorizanthe brevicornu var. brevicornu	brittle spineflower	3
175	Pol	Chorizanthe corrugata	wrinkled spineflower	x
176	Pol	Chorizanthe rigida	devil's spineflower	iN
177	Pol	Eriogonum inflatum	desert trumpet	x
178	Pol	Eriogonum thomasii	Thomas' buckwheat	x
179	Pol	Eriogonum trichopes	little desert trumpet	20
180	Pol	Pterostegia drymarioides	fairy bowties, threadstem	iN
181	Res	Oligomeris linifolia	lineleaf whitepuff	99
182	Sim	Simmondsia chinensis	jojoba	20
183	Sol	Lycium brevipes var. brevipes	desert boxthorn	99
184	Sol	Nicotiana clevelandii	Cleveland's tobacco	V
185	Tam	Tamarix aphylla	*athel	5
186	Tam	Tamarix ramosissima	*saltcedar	5
187	Vis	Phoradendron californicum	desert mistletoe	99
188	Zyg	Fagonia laevis	California fagonia	x
189	Zyg	Fagonia pachyacantha	sticky fagonia	x
190	Zyg	Kallstroemia californica	California caltrop	iN
191	Zyg	Larrea tridentata	creosote bush	99
Monocots
192	Aga	Hesperocallis undulata	desert lily	50
193	Poa	Aristida adscensionis	six-weeks three-awn	V
194	Poa	Hilaria rigida	big galleta	80
195	Poa	Phalaris minor	*little-seed canarygrass	iN
196	Poa	Schismus barbatus	*Mediterranean schismus	99
197	Poa	Stipa hymenoides	Indian ricegrass	iN

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Voucher data provided by the participants of the Consortium of California Herbaria (ucjeps.berkeley.edu/consortium/)

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