Flora of Lake Henshaw, San Diego County

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


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:

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.

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)

#FamScientific Name(*)Common Name#V#Pls
1AizoaCypselea humifusa*panal299
2AmaraAmaranthus albus*tumble pigweed2 
3AmaraAmaranthus californicusCalifornia amaranth5 
4AmaraAmaranthus palmeriPalmer's amaranth1 
5ApiacCicuta maculataspotted water hemlock1 
6ApiacSanicula bipinnatifidapurple sanicle3 
7AscleAsclepias eriocarpaIndian milkweed2 
8AsterAmbrosia acanthicarpabur-ragweed1 
9AsterAmbrosia psilostachyawestern ragweed299
10AsterAnisocoma acaulisscale-bud1 
11AsterArtemisia douglasianamugwort3 
12AsterArtemisia dracunculuswild tarragon1 
13AsterArtemisia tridentata ssp. tridentatabig sagebrush2 
14AsterAster frondosusshort-rayed alkali aster51
15AsterBaccharis pilulariscoyote bush1 
16AsterBrickellia californicaCalifornia brickellbush1 
17AsterCentaurea maculosa*spotted knapweed2 
18AsterChaenactis glabriuscula var. lanosawoolly yellow chaenactis1 
19AsterCichorium intybus*chicory199
20AsterCirsium scariosumelk thistle1 
21AsterCirsium vulgare*bull thistle2 
22AsterConyza canadensishorseweed320
23AsterEclipta prostratafalse daisy2 
24AsterEuthamia occidentaliswestern goldenrod2 
25AsterGnaphalium canescens ssp. beneolensfragrant everlasting1 
26AsterGnaphalium luteo-album*common cudweed399
27AsterGnaphalium palustrewestern marsh cudweed250
28AsterGrindelia hirsutula var. halliiSan Diego gumplant 30
29AsterGutierrezia californicaCalifornia matchweed2 
30AsterHeterotheca grandifloratelegraph weed150
31AsterHeterotheca sessiliflora ssp. echioidesbristly goldenaster3 
32AsterLactuca serriola*prickly lettuce2 
33AsterLagophylla ramosissima ssp. ramosissimacommon hareleaf1 
34AsterLasthenia californicagoldfields2 
35AsterLepidospartum squamatumscale-broom2 
36AsterLessingia filaginifolia var. filaginifoliaCalifornia-aster199
37AsterLessingia glandulifera var. glanduliferasticky lessingia1 
38AsterLessingia glandulifera var. tomentosaWarner Springs lessingia6 
39AsterMalacothrix californicaCalifornia dandelion2 
40AsterSenecio flaccidus var. monoensisMono ragwort1 
41AsterSolidago californicagoldenrod2 
42AsterSolidago confinissouthern goldenrod1 
43AsterSonchus asper ssp. asper*prickly sow thistle250
44AsterSonchus oleraceus*sow thistle2 
45AsterStephanomeria exigua ssp. deaneislender wreathplant2 
46AsterUropappus lindleyisilver puffs1 
47AsterXanthium strumariumcocklebur299
48BoragHeliotropium curassavicumseaside heliotrope2 
49BoragPectocarya penicillatacombseed1 
50BoragPlagiobothrys arizonicusArizona popcorn flower1 
51BoragPlagiobothrys nothofulvusrusty-haired popcorn flower199
52BrassHirschfeldia incana*shortpod mustard250
53BrassRorippa palustris var. occidentaliswestern bog yellow-cress1 
54BrassRorippa tenerrimaModoc yellow-cress2 
55BrassSisymbrium altissimum*tumble-mustard1 
56CampaLobelia cardinalis var. pseudosplendenscardinal flower3 
57CapriLonicera hispidula var. vacillanshairy honeysuckle1 
58CapriSambucus mexicanablue elderberry1 
59CapriSymphoricarpos molliscreeping snowberry1 
60CaryoCerastium glomeratum*mouse-ear chickweed2 
61CaryoSpergularia bocconei*sand spurrey1 
62ChenoChenopodium album*white goosefoot1 
63ChenoChenopodium ambrosioides*Mexican tea2 
64ChenoChenopodium berlandieripit-seed goosefoot1 
65ChenoChenopodium glaucum*oak-leaved goosefoot2 
66ChenoChenopodium multifidum*cut-leaved goosefoot1 
67ChenoSalsola tragus*Russian thistle2 
68CucurCucurbita foetidissimastinking gourd2 
69CuscuCuscuta californica var. californicaCalifornia dodder1 
70DatisDatisca glomerataDurango root1 
71EuphoChamaesyce maculata*spotted spurge2 
72EuphoCroton californicusCalifornia croton1 
73EuphoEremocarpus setigerusdove weed199
74FabacAmorpha fruticosawestern false-indigo1 
75FabacLathyrus vestitus var. alefeldiiSan Diego pea1 
76FabacLotus corniculatus*bird's-foot lotus2 
77FabacLotus heermannii var. heermanniisilky lotus12
78FabacLotus oblongifolius var. oblongifoliusstreambank lotus1 
79FabacLotus purshianus var. purshianusSpanish clover3 
80FabacLotus strigosusstrigose lotus2 
81FabacLupinus bicolordwarf lupine5 
82FabacLupinus concinnusbajada lupine1 
83FabacLupinus microcarpus var. densifloruschick lupine1 
84FabacMedicago lupulina*black medick2 
85FabacMelilotus albus*white sweetclover1 
86FabacMelilotus indicus*sourclover2 
87FabacTrifolium albopurpureum var. albopurpureumIndian clover1 
88FabacTrifolium microcephalumsmall-head field clover1 
89FabacVicia villosa*purple vetch1 
90FagacQuercus acutidensTorrey's scrub oak2 
91FagacQuercus agrifoliacoast live oak1 
92FagacQuercus agrifolia var. oxyadeniasouthern coast live oak2 
93FagacQuercus engelmanniiEngelmann oak1 
94GentiCentaurium venustumcanchalagua1 
95GeranErodium cicutarium*redstem filaree150
96HydroEriodictyon crassifolium var. nigrescensthick-leaved yerba santa1 
97HydroNama stenocarpummud nama299
98LamiaMarrubium vulgare*horehound1 
99LamiaMentha spicata var. spicata*spearmint1 
100LamiaScutellaria bolanderi ssp. austromontanasouthern skullcap1 
101LamiaStachys ajugoides var. rigidarigid hedge-nettle4 
102LamiaTrichostema lanceolatumvinegar weed1 
103LythrLythrum hyssopifolia*grass poly2 
104MalvaMalvella leprosaalkali mallow299
105MalvaSidalcea malviflora ssp. sparsifoliacheckerbloom2 
106MolluGlinus lotoides*lotus sweetjuice2 
107OleacFraxinus velutinavelvet ash1 
108OnagrCamissonia strigulosastrigose sun-cup1 
109OnagrEpilobium brachycarpumautumn willowweed2 
110OnagrEpilobium canum ssp. latifoliummountain California-fuchsia1 
111OnagrEpilobium ciliatum ssp. ciliatumwillowherb2 
112OnagrEpilobium densiflorumspike primrose1 
113OnagrLudwigia peploides ssp. peploidesfloating water-primrose1 
114OnagrOenothera elata ssp. hirsutissimaHooker's evening-primrose1 
115PapavDendromecon rigidabush poppy1 
116PapavEschscholzia californicaCalifornia poppy1 
117PapavMeconella denticulatasmall-flowered meconella1 
118PlantPlantago major*common plantain2 
119PolemGilia capitata ssp. abrotanifoliaCalifornia gilia1 
120PolemGilia clivorumpurple-spot gilia1 
121PolemGilia diegensiscoastal gilia2 
122PolemLinanthus dianthiflorusground pink1 
123PolemLinanthus liniflorusflax-flowered linanthus2 
124PolemNavarretia atractyloidesholly-leaf navarretia1 
125PolemPhlox gracilisannual phlox1 
126PolygEriogonum elongatum var. elongatumlong-stemmed buckwheat1 
127PolygEriogonum fasciculatum var. foliolosumCalifornia buckwheat1 
128PolygEriogonum gracile var. gracileslender buckwheat2 
129PolygEriogonum gracile var. incultumslender buckwheat3 
130PolygPolygonum arenastrum*knotweed3 
131PolygPolygonum argyrocoleon*silver-sheath knotweed2 
132PolygPolygonum lapathifoliumwillow weed3 
133PolygRumex conglomeratus*whorled dock1 
134PolygRumex crispus*curly dock299
135PolygRumex maritimusgolden dock320
136PolygRumex pulcher*fiddle dock1 
137PolygRumex salicifolius var. denticulatuswillow-leaved dock2 
138RanunRanunculus californicusCalifornia buttercup150
139RanunRanunculus cymbalaria var. saximontanusRocky Mountain buttercup5 
140RanunRanunculus sceleratuscursed crowfoot2 
141RhamnCeanothus palmeriPalmer's ceanothus1 
142RhamnRhamnus tomentella ssp. tomentellahoary coffeeberry1 
143RosacAdenostoma fasciculatumchamise1 
144RosacCercocarpus betuloides var. betuloidesbirch-leaf mountain-mahogany2 
145RosacPrunus emarginatabitter cherry1 
146RubiaGalium porrigens var. porrigensgraceful bedstraw1 
147SalicSalix gooddingiiblack willow1 
148SalicSalix laevigatared willow1 
149SalicSalix lasiolepisarroyo willow3 
150ScropCastilleja exserta ssp. exsertapurple owl's-clover1 
151ScropCastilleja minor ssp. spiralislesser paintbrush1 
152ScropCordylanthus rigidus ssp. setigerusbristly bird's beak1 
153ScropMimulus cardinalisscarlet monkeyflower1 
154ScropMimulus pilosusfalse monkeyflower1 
155ScropPenstemon centranthifoliusscarlet bugler1 
156ScropPenstemon Xparishii (P. centranthifolius X P. spectabilis var. spectabilis)Parish's penstemon1 
157ScropScrophularia californica ssp. floribundaCalifornia bee plant1 
158ScropVerbascum blattaria*moth mullein3 
159ScropVerbascum thapsus*common mullein3 
160ScropVeronica anagallis-aquatica*water speedwell3 
161SolanNicotiana attenuatacoyote tobacco2 
162SolanNicotiana quadrivalvisIndian tobacco1 
163SolanPetunia parviflorawild petunia499
164SolanSolanum americanumsmall-flowered nightshade2 
165TamarTamarix ramosissima*saltcedar199
166UrticUrtica dioica ssp. holosericeastinging nettle2 
167ValerPlectritis ciliosa ssp. insignislong-spurred plectritis1 
168VerbePhyla nodiflora var. nodifloracommon lippia3 
169VerbeVerbena bracteatabracted verbena210
170VerbeVerbena lasiostachys var. scabridawestern vervain3 
171ViolaViola sororia ssp. affinisnorthern bog violet1 
172ViscaPhoradendron macrophyllumbig leaf mistletoe110
173CyperCarex praegracilisclustered field sedge1 
174CyperCyperus eragrostisumbrella sedge1 
175CyperCyperus erythrorhizosredroot flatsedge299
176CyperCyperus squarrosusbearded flatsedge1 
177CyperEleocharis montevidensissand spikerush1 
178CyperEleocharis parishiiParish's spikerush2 
179CyperEleocharis radicanscreeping spikerush2 
180JuncaJuncus balticuswire rush1 
181JuncaJuncus bufonius var. congestusclustered toad rush3 
182JuncaJuncus dubiusMariposa rush1 
183JuncaJuncus mexicanusMexican rush199
184PoaceBromus arenarius*Australian brome1 
185PoaceBromus madritensis ssp. madritensis*foxtail chess1 
186PoaceCrypsis schoenoides*swamp grass399
187PoaceCynodon dactylon*Bermuda grass399
188PoaceEchinochloa crus-pavonis*gulf cockspur grass1 
189PoaceLeptochloa fascicularissprangletop230
190PoaceMuhlenbergia rigensdeergrass1 
191PoacePhragmites australiscommon reed1 
192PoacePolypogon monspeliensis*rabbits-foot grass220
193PotamPotamogeton pectinatusfennel-leaved pondweed1 

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

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Copyright © 2012 by Tom Chester
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Last update: 17 November 2012