Flora of Lake Henshaw, San Diego County

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Introduction
Procedure for Compiling the Checklist
Observations from 15 November 2012
Plant Checklist

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Introduction

Lake Henshaw is a reservoir for the Vista Irrigation District, who owns the vast majority of the watershed, including the 43,000 acre Warner Ranch. Henshaw Dam was built in 1923. Lake Henshaw dams the upper reaches of the San Luis Rey River, in a broad flat area separating three mountain ranges: the Palomar Mountains to the northwest; the Hot Springs / San Ysidro Mountains to the northeast; and the Volcan Mountains to the east.

The dam is now operated to keep it below 40% capacity since it is built right on the Elsinore Fault. The fluctuating lake level creates habitat for native species that live in drying lake margins, as well as a large amount of disturbed habitat that is now dominated by non-native weeds.

Procedure for Compiling the Checklist

This checklist was compiled from a search of the Consortium of California Herbaria on 16 November 2012, with some abundances given from plants incidentally noted on a hike along the eastern end of Lake Henshaw on 15 November 2012, as well as some species seen from previous stops in the area of the Eagle's Nest turnout, the one with the turnstile. The lake was just 6% full at the time of that hike.

The vouchers came from a geographic search for georeferenced vouchers between 33.20 and 33.29° latitude, and -116.76 to -116.69° longitude. The localities of the vouchers were reviewed, and ones not clearly from Lake Henshaw were tossed. I did not do a separate search for vouchers without coordinates that had a locality of Lake Henshaw since my main goal was just to identify a small number of nearly-dead species I photographed on 15 November 2012, and it would have taken more work to go through those localities to retrieve just the Lake Henshaw vouchers.

Since most of the plants I photographed were not in good enough shape to key out, I got the identifications by matching column A (the vouchered species) with column B (my pictures). (;-) This was actually fairly easy since I knew all the species in the checklist except for about 10, to match with 7 species I photographed that I had never seen before.

Of course, if the plants in my photographs aren't on the voucher list, or the voucher determination is incorrect, or I screwed up in matching column A with column B, I'll have the wrong determination.

Some pictures from the 15 November 2012 trip are in a temporary directory. If anyone notices an error, please let me know.

Observations from 15 November 2012

The extensive dry lake area is a very unusual place, one I've never botanized before. It contained a large number of species I haven't seen anywhere else, and it has huge stands of a few species.

Species I've seen only in this area

I was totally dumbfounded when I went through my pictures and identified SEVEN species I've never seen before, with six of them native!!! It is fairly unusual for me to find even a single species new to me on a trip; to find seven is astounding. The reason for all these new species for me, of course, is that I've never botanized a drying lake margin before, at least of a big lake like this one.

The seven species new to me are:

• Aster frondosus
• Cyperus erythrorhizos
• *Cypselea humifusa
• Leptochloa fascicularis
• Nama stenocarpum
• Rumex maritimus
• Verbena bracteata

Non-native species are marked with *.

In addition, this area is the only place I've ever seen the real chicory, *Cichorium intybus, which grows abundantly right by the turnstile and which I've seen on numerous stops here in the past.

Furthermore, my pix showed three other species I've only recorded in my database once before from my trips; two of those are native.

• *Crypsis schoenoides
• Malvella leprosa
• Petunia parviflora

World-Class Monocultures of a few species

On the south east side of the Lake, there is a huge field of *common cudweed, Gnaphalium luteo-album, that went on for almost as far as the eye can see in one area. See one of four photographs in a panorama covering only part of the field. This has to be the world's largest stand of cudweed (the white / gray erect thin stalks, not the low brown stuff).

By far, the most numerous large plant in the entire basin here is the world-wide-native cocklebur, Xanthium strumarium. Here are just three representative shots in a 360 panorama showing some of the plants: Pano shot #2 facing southeast; Pano shot #4 facing east toward the northern part of the Volcan Mountains; and Pano shot #7 facing north toward Monkey Hill.

This again has to be world-class in the numbers of plants.

Furthermore, this plant is no slouch at producing seeds! Every stem is filled with dozens of seeds, ready to jump onto one's pants, shoes and shoe-laces if you get within whispering distance of them. Our main goal through this hike was to try to avoid getting cockle-burred-up.

There were also world-class stands of *Bermuda grass, Cynodon dactylon; redroot flatsedge, Cyperus erythrorhizos; *panal, Cypselea humifusa, mud nama, Nama stenocarpum, and wild petunia, Petunia parviflora.

Plant Checklist

This following checklist, made from vouchers and my observations, is in the 1993 First Edition Jepson Manual format.

The column Fam gives the first five letters of the family name.

An asterisk before the common name indicates a taxon not-native to California.

The column #V gives the number of vouchers for each species.

The column #Pls indicates the number of plants observed of some species on 15 November 2012 and previously. That list was filled out from memory on 16 November 2012, and so is incomplete. Now that I've started a list for this area, I'll attempt to record the species more systematically on future trips here.

Version for printing, without lines and other text on this page: html (6 pages) or pdf Clickbook booklet (2 double-sided pages). (See printing instructions for an explanation of these options)

#	Fam	Scientific Name	(*)Common Name	#V	#Pls
1	Aizoa	Cypselea humifusa	*panal	2	99
2	Amara	Amaranthus albus	*tumble pigweed	2
3	Amara	Amaranthus californicus	California amaranth	5
4	Amara	Amaranthus palmeri	Palmer's amaranth	1
5	Apiac	Cicuta maculata	spotted water hemlock	1
6	Apiac	Sanicula bipinnatifida	purple sanicle	3
7	Ascle	Asclepias eriocarpa	Indian milkweed	2
8	Aster	Ambrosia acanthicarpa	bur-ragweed	1
9	Aster	Ambrosia psilostachya	western ragweed	2	99
10	Aster	Anisocoma acaulis	scale-bud	1
11	Aster	Artemisia douglasiana	mugwort	3
12	Aster	Artemisia dracunculus	wild tarragon	1
13	Aster	Artemisia tridentata ssp. tridentata	big sagebrush	2
14	Aster	Aster frondosus	short-rayed alkali aster	5	1
15	Aster	Baccharis pilularis	coyote bush	1
16	Aster	Brickellia californica	California brickellbush	1
17	Aster	Centaurea maculosa	*spotted knapweed	2
18	Aster	Chaenactis glabriuscula var. lanosa	woolly yellow chaenactis	1
19	Aster	Cichorium intybus	*chicory	1	99
20	Aster	Cirsium scariosum	elk thistle	1
21	Aster	Cirsium vulgare	*bull thistle	2
22	Aster	Conyza canadensis	horseweed	3	20
23	Aster	Eclipta prostrata	false daisy	2
24	Aster	Euthamia occidentalis	western goldenrod	2
25	Aster	Gnaphalium canescens ssp. beneolens	fragrant everlasting	1
26	Aster	Gnaphalium luteo-album	*common cudweed	3	99
27	Aster	Gnaphalium palustre	western marsh cudweed	2	50
28	Aster	Grindelia hirsutula var. hallii	San Diego gumplant		30
29	Aster	Gutierrezia californica	California matchweed	2
30	Aster	Heterotheca grandiflora	telegraph weed	1	50
31	Aster	Heterotheca sessiliflora ssp. echioides	bristly goldenaster	3
32	Aster	Lactuca serriola	*prickly lettuce	2
33	Aster	Lagophylla ramosissima ssp. ramosissima	common hareleaf	1
34	Aster	Lasthenia californica	goldfields	2
35	Aster	Lepidospartum squamatum	scale-broom	2
36	Aster	Lessingia filaginifolia var. filaginifolia	California-aster	1	99
37	Aster	Lessingia glandulifera var. glandulifera	sticky lessingia	1
38	Aster	Lessingia glandulifera var. tomentosa	Warner Springs lessingia	6
39	Aster	Malacothrix californica	California dandelion	2
40	Aster	Senecio flaccidus var. monoensis	Mono ragwort	1
41	Aster	Solidago californica	goldenrod	2
42	Aster	Solidago confinis	southern goldenrod	1
43	Aster	Sonchus asper ssp. asper	*prickly sow thistle	2	50
44	Aster	Sonchus oleraceus	*sow thistle	2
45	Aster	Stephanomeria exigua ssp. deanei	slender wreathplant	2
46	Aster	Uropappus lindleyi	silver puffs	1
47	Aster	Xanthium strumarium	cocklebur	2	99
48	Borag	Heliotropium curassavicum	seaside heliotrope	2
49	Borag	Pectocarya penicillata	combseed	1
50	Borag	Plagiobothrys arizonicus	Arizona popcorn flower	1
51	Borag	Plagiobothrys nothofulvus	rusty-haired popcorn flower	1	99
52	Brass	Hirschfeldia incana	*shortpod mustard	2	50
53	Brass	Rorippa palustris var. occidentalis	western bog yellow-cress	1
54	Brass	Rorippa tenerrima	Modoc yellow-cress	2
55	Brass	Sisymbrium altissimum	*tumble-mustard	1
56	Campa	Lobelia cardinalis var. pseudosplendens	cardinal flower	3
57	Capri	Lonicera hispidula var. vacillans	hairy honeysuckle	1
58	Capri	Sambucus mexicana	blue elderberry	1
59	Capri	Symphoricarpos mollis	creeping snowberry	1
60	Caryo	Cerastium glomeratum	*mouse-ear chickweed	2
61	Caryo	Spergularia bocconei	*sand spurrey	1
62	Cheno	Chenopodium album	*white goosefoot	1
63	Cheno	Chenopodium ambrosioides	*Mexican tea	2
64	Cheno	Chenopodium berlandieri	pit-seed goosefoot	1
65	Cheno	Chenopodium glaucum	*oak-leaved goosefoot	2
66	Cheno	Chenopodium multifidum	*cut-leaved goosefoot	1
67	Cheno	Salsola tragus	*Russian thistle	2
68	Cucur	Cucurbita foetidissima	stinking gourd	2
69	Cuscu	Cuscuta californica var. californica	California dodder	1
70	Datis	Datisca glomerata	Durango root	1
71	Eupho	Chamaesyce maculata	*spotted spurge	2
72	Eupho	Croton californicus	California croton	1
73	Eupho	Eremocarpus setigerus	dove weed	1	99
74	Fabac	Amorpha fruticosa	western false-indigo	1
75	Fabac	Lathyrus vestitus var. alefeldii	San Diego pea	1
76	Fabac	Lotus corniculatus	*bird's-foot lotus	2
77	Fabac	Lotus heermannii var. heermannii	silky lotus	1	2
78	Fabac	Lotus oblongifolius var. oblongifolius	streambank lotus	1
79	Fabac	Lotus purshianus var. purshianus	Spanish clover	3
80	Fabac	Lotus strigosus	strigose lotus	2
81	Fabac	Lupinus bicolor	dwarf lupine	5
82	Fabac	Lupinus concinnus	bajada lupine	1
83	Fabac	Lupinus microcarpus var. densiflorus	chick lupine	1
84	Fabac	Medicago lupulina	*black medick	2
85	Fabac	Melilotus albus	*white sweetclover	1
86	Fabac	Melilotus indicus	*sourclover	2
87	Fabac	Trifolium albopurpureum var. albopurpureum	Indian clover	1
88	Fabac	Trifolium microcephalum	small-head field clover	1
89	Fabac	Vicia villosa	*purple vetch	1
90	Fagac	Quercus acutidens	Torrey's scrub oak	2
91	Fagac	Quercus agrifolia	coast live oak	1
92	Fagac	Quercus agrifolia var. oxyadenia	southern coast live oak	2
93	Fagac	Quercus engelmannii	Engelmann oak	1
94	Genti	Centaurium venustum	canchalagua	1
95	Geran	Erodium cicutarium	*redstem filaree	1	50
96	Hydro	Eriodictyon crassifolium var. nigrescens	thick-leaved yerba santa	1
97	Hydro	Nama stenocarpum	mud nama	2	99
98	Lamia	Marrubium vulgare	*horehound	1
99	Lamia	Mentha spicata var. spicata	*spearmint	1
100	Lamia	Scutellaria bolanderi ssp. austromontana	southern skullcap	1
101	Lamia	Stachys ajugoides var. rigida	rigid hedge-nettle	4
102	Lamia	Trichostema lanceolatum	vinegar weed	1
103	Lythr	Lythrum hyssopifolia	*grass poly	2
104	Malva	Malvella leprosa	alkali mallow	2	99
105	Malva	Sidalcea malviflora ssp. sparsifolia	checkerbloom	2
106	Mollu	Glinus lotoides	*lotus sweetjuice	2
107	Oleac	Fraxinus velutina	velvet ash	1
108	Onagr	Camissonia strigulosa	strigose sun-cup	1
109	Onagr	Epilobium brachycarpum	autumn willowweed	2
110	Onagr	Epilobium canum ssp. latifolium	mountain California-fuchsia	1
111	Onagr	Epilobium ciliatum ssp. ciliatum	willowherb	2
112	Onagr	Epilobium densiflorum	spike primrose	1
113	Onagr	Ludwigia peploides ssp. peploides	floating water-primrose	1
114	Onagr	Oenothera elata ssp. hirsutissima	Hooker's evening-primrose	1
115	Papav	Dendromecon rigida	bush poppy	1
116	Papav	Eschscholzia californica	California poppy	1
117	Papav	Meconella denticulata	small-flowered meconella	1
118	Plant	Plantago major	*common plantain	2
119	Polem	Gilia capitata ssp. abrotanifolia	California gilia	1
120	Polem	Gilia clivorum	purple-spot gilia	1
121	Polem	Gilia diegensis	coastal gilia	2
122	Polem	Linanthus dianthiflorus	ground pink	1
123	Polem	Linanthus liniflorus	flax-flowered linanthus	2
124	Polem	Navarretia atractyloides	holly-leaf navarretia	1
125	Polem	Phlox gracilis	annual phlox	1
126	Polyg	Eriogonum elongatum var. elongatum	long-stemmed buckwheat	1
127	Polyg	Eriogonum fasciculatum var. foliolosum	California buckwheat	1
128	Polyg	Eriogonum gracile var. gracile	slender buckwheat	2
129	Polyg	Eriogonum gracile var. incultum	slender buckwheat	3
130	Polyg	Polygonum arenastrum	*knotweed	3
131	Polyg	Polygonum argyrocoleon	*silver-sheath knotweed	2
132	Polyg	Polygonum lapathifolium	willow weed	3
133	Polyg	Rumex conglomeratus	*whorled dock	1
134	Polyg	Rumex crispus	*curly dock	2	99
135	Polyg	Rumex maritimus	golden dock	3	20
136	Polyg	Rumex pulcher	*fiddle dock	1
137	Polyg	Rumex salicifolius var. denticulatus	willow-leaved dock	2
138	Ranun	Ranunculus californicus	California buttercup	1	50
139	Ranun	Ranunculus cymbalaria var. saximontanus	Rocky Mountain buttercup	5
140	Ranun	Ranunculus sceleratus	cursed crowfoot	2
141	Rhamn	Ceanothus palmeri	Palmer's ceanothus	1
142	Rhamn	Rhamnus tomentella ssp. tomentella	hoary coffeeberry	1
143	Rosac	Adenostoma fasciculatum	chamise	1
144	Rosac	Cercocarpus betuloides var. betuloides	birch-leaf mountain-mahogany	2
145	Rosac	Prunus emarginata	bitter cherry	1
146	Rubia	Galium porrigens var. porrigens	graceful bedstraw	1
147	Salic	Salix gooddingii	black willow	1
148	Salic	Salix laevigata	red willow	1
149	Salic	Salix lasiolepis	arroyo willow	3
150	Scrop	Castilleja exserta ssp. exserta	purple owl's-clover	1
151	Scrop	Castilleja minor ssp. spiralis	lesser paintbrush	1
152	Scrop	Cordylanthus rigidus ssp. setigerus	bristly bird's beak	1
153	Scrop	Mimulus cardinalis	scarlet monkeyflower	1
154	Scrop	Mimulus pilosus	false monkeyflower	1
155	Scrop	Penstemon centranthifolius	scarlet bugler	1
156	Scrop	Penstemon Xparishii (P. centranthifolius X P. spectabilis var. spectabilis)	Parish's penstemon	1
157	Scrop	Scrophularia californica ssp. floribunda	California bee plant	1
158	Scrop	Verbascum blattaria	*moth mullein	3
159	Scrop	Verbascum thapsus	*common mullein	3
160	Scrop	Veronica anagallis-aquatica	*water speedwell	3
161	Solan	Nicotiana attenuata	coyote tobacco	2
162	Solan	Nicotiana quadrivalvis	Indian tobacco	1
163	Solan	Petunia parviflora	wild petunia	4	99
164	Solan	Solanum americanum	small-flowered nightshade	2
165	Tamar	Tamarix ramosissima	*saltcedar	1	99
166	Urtic	Urtica dioica ssp. holosericea	stinging nettle	2
167	Valer	Plectritis ciliosa ssp. insignis	long-spurred plectritis	1
168	Verbe	Phyla nodiflora var. nodiflora	common lippia	3
169	Verbe	Verbena bracteata	bracted verbena	2	10
170	Verbe	Verbena lasiostachys var. scabrida	western vervain	3
171	Viola	Viola sororia ssp. affinis	northern bog violet	1
172	Visca	Phoradendron macrophyllum	big leaf mistletoe	1	10
173	Cyper	Carex praegracilis	clustered field sedge	1
174	Cyper	Cyperus eragrostis	umbrella sedge	1
175	Cyper	Cyperus erythrorhizos	redroot flatsedge	2	99
176	Cyper	Cyperus squarrosus	bearded flatsedge	1
177	Cyper	Eleocharis montevidensis	sand spikerush	1
178	Cyper	Eleocharis parishii	Parish's spikerush	2
179	Cyper	Eleocharis radicans	creeping spikerush	2
180	Junca	Juncus balticus	wire rush	1
181	Junca	Juncus bufonius var. congestus	clustered toad rush	3
182	Junca	Juncus dubius	Mariposa rush	1
183	Junca	Juncus mexicanus	Mexican rush	1	99
184	Poace	Bromus arenarius	*Australian brome	1
185	Poace	Bromus madritensis ssp. madritensis	*foxtail chess	1
186	Poace	Crypsis schoenoides	*swamp grass	3	99
187	Poace	Cynodon dactylon	*Bermuda grass	3	99
188	Poace	Echinochloa crus-pavonis	*gulf cockspur grass	1
189	Poace	Leptochloa fascicularis	sprangletop	2	30
190	Poace	Muhlenbergia rigens	deergrass	1
191	Poace	Phragmites australis	common reed	1
192	Poace	Polypogon monspeliensis	*rabbits-foot grass	2	20
193	Potam	Potamogeton pectinatus	fennel-leaved pondweed	1

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

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