Plant Guide to Mt. Wilson Toll Road / Horse Trail Loop, Eaton Canyon, San Gabriel Mountains This is a working list, about which we make no guarantees at all until we officially release it. Use at your own risk!
Introduction and Explanation of Plant Trail Guides
Introduction
Highlights of This Trail
Plant Communities and Floristics
Fieldwork Dates and Summary of List Changes With Time
The Plant Guide
Comments On Specific Species
Introduction Directions to the trailhead:
From I-210 East: Take the Altadena Drive Exit, and go north on Altadena Drive.
From I-210 West: Take the San Gabriel Boulevard Exit (signed for Eaton Canyon Nature Center), continue past Sierra Madre to Altadena Drive, and turn right (north) on Altadena Drive.Take Altadena Drive north about 2.5 miles to Crescent Drive and turn right. Turn right at the next block, Pinecrest Drive. The trailhead is at the gate as Pinecrest Drive curves left.
Parking on Pinecrest Drive is limited to 2 hours on the weekdays and not at all on the weekends, thanks to the selfish neighbors there (see 26-1 Eaton Canyon Nature Center to Henninger Flats). So if you'll be there more than 2 hours, simply park one block away.
See also Eaton Canyon and Flora of Lower Eaton Canyon.
Highlights of This Trail Most people would consider this trail to be in coastal sage scrub. Believe it or not, this trail is in the Mixed Hardwood Forest vegetation classification of Kuchler.
Our list contains 120 taxa, of which 117 have so far been identified, in about 1.49 miles of trail, and 2 of the unidentified species are clearly planted and non-native to Eaton Canyon. Of these 119 taxa, 36 (30%) are non-native. These numbers are all roughly average for trails at this elevation.
The botanical highlights of this trail are:
Plant Communities and Floristics Number of Unique Taxa On This Trail
The following histogram gives the number of trails in our database that contain each taxon on this trail. We had 73 trails in our database when this histogram was made; 3 of those trails, including this one, are in Eaton Canyon. A number of "1" means the taxon has only been found on this trail among the trails in our database; numbers of "3" or smaller may indicate taxa found only in this area. A number of "1" means the taxon has only been found on this trail among the trails in our database.
We have two additional trails about six miles to the west / northwest.
Number of Trails
Containing A TaxonNumber Of Taxa
On This Trail% of Taxa
On This Trail1 6 5% 2 3 3% 3 5 4% 4 3 3% 5 3 3% 1-5 20 17% 6-10 17 15% 11-15 28 24% 16-20 16 14% 21-25 9 8% 26-30 12 10% 31-35 11 9% 36-40 4 3% Total Taxa 117 100% We found 3 additional species not in the above table, since they have not been identified yet. The unidentified ones are marked with ? or sp in the id? column in the guide, and have no entries in the #all column.
The taxa that are truly unique to this trail or area, out of our 73 trails on 24 January 2004, are:
#all Latin Name Common Name Distribution in Southern California / Distribution in Trail Guides 1 Camissonia confusa San Bernardino sun-cup SW. It may be uncommon because it is possibly a hybrid between C. hirtella and C. pallida ssp. pallida. 1 Encelia actoni Acton's encelia sw SnJV and adjacent WTR (Cuyama Valley), w D and adjacent CA-FP. Possibly introduced into this location through seeds carried on automobile tires from near Acton. 1 Castilleja foliolosa woolly Indian paintbrush The Jepson Manual thinks it is only in s ChI, but Munz says coastal sage scrub, chaparral from Baja to northern California. We have it in 15 floras in Southern California. 1 Coreopsis bigelovii Bigelow's coreopsis TR, DMoj, n Dson. 2 Lepidium virginicum var. robinsonii Robinson's pepper-grass Uncommon; SW. 2 Quercus durata var. gabrielensis X Q. engelmannii Engelmann leather oak hybrid SnGb (s slope) 3 Delphinium cardinale scarlet larkspur SW. We have it only in 3 front-range SnGb trails. 3 Chenopodium botrys Jerusalem oak Most of California. We have it only in 2 front-range SnGb trails plus the Manzanita Trail on Mt. Baden-Powell in the SnGb. 3 Quercus durata var. gabrielensis San Gabriel Mtns. leather oak SnGb (s slope) 3 Juglans californica var. californica Southern California black walnut SCo, s TR, n PR (Santa Ana Mountains). We have it only in 3 front-range SnGb trails. The following taxa are listed as being found only on this trail or in this area, but are planted specimens:
#all Latin Name Common Name Comment 1 Quercus lobata Valley oak Native to nw SCo, ChI, WTR, w SnGb, but not to Eaton Canyon. 1 Casuarina equisetifolia Australian pine Planted species; non-native. The following taxa are listed as being found only on this trail or in this area, but are not unique for the reasons given below:
#all Latin Name Common Name Comment 2 Eriodictyon crassifolium thick-leaved yerba santa ssp id needed 3 Hordeum murinum foxtail barley plants do not key to subspecies Both of these are common taxa, which have been identified to subspecies in many other trail lists.
Fieldwork Dates and Summary of List Changes With Time The following table gives the dates the trail was walked and taxa recorded. After each visit, the table gives the total number of taxa on the list and the breakdown of the taxa without positive identification. See Explanation of Plant Trail Guides to understand the symbols below.
Visit Date Visit # # taxa # "?" # "sp" # "~" # "ssp" 3/27/2003 1 121 3 3 6 7 1/22/2004 2 120 2 3 3 1 Only the first 0.16 miles was covered on 1/22/04.
We thank Jason Hollinger for the correct identification of Chamaesyce melanadenia in February 2006.
The Plant Guide Version for printing, without lines and other text on this page (5 pages)
Mile s # id? Common Name Latin Name #here #all 0.00 Begin plant guide immediately after passing through gate at Pinecrest Drive; elevation 1320 feet. 0.00 r 1 mule fat Baccharis salicifolia 5 / 2 28 0.00 r 2 wild-cucumber Marah macrocarpus var. macrocarpus 5 / 2 34 0.00 r 3 *smilo grass Piptatherum miliaceum 50 / 9 16 0.00 r 4 California sagebrush Artemisia californica / 32 0.00 r 5 *ripgut brome Bromus diandrus / 34 0.00 r 6 branching phacelia Phacelia ramosissima var. latifolia 20 / 5 23 0.00 r 7 *shortpod mustard Hirschfeldia incana 50 / 9 38 0.00 r 8 *Oriental mustard Sisymbrium orientale / 7 0.00 r 9 *white goosefoot Chenopodium album 20 / 2 11 0.00 r 10 bur-ragweed Ambrosia acanthicarpa 20 / 4 13 0.00 r 11 *foxtail barley Hordeum murinum+ 99 / 9 3 0.00 r 12 *redstem filaree Erodium cicutarium 50 / 5 32 0.00 r 13 California buckwheat Eriogonum fasciculatum var. foliolosum 30 / 5 38 0.00 r 14 lanceleaf dudleya Dudleya lanceolata 30 / 3 16 0.00 r 15 coast live oak Quercus agrifolia var. agrifolia 3 / 3 31 0.00 l 16 short-leaved cliff-aster Malacothrix saxatilis var. tenuifolia 20 / 5 9 0.01 l 17 *tree tobacco Nicotiana glauca 20 / 5 15 0.01 l 18 short-winged deerweed Lotus scoparius var. brevialatus+ 20 / 5 13 0.01 l 19 California brickellbush Brickellia californica 20 / 5 23 0.01 r 20 *slender wild oats Avena barbata / 19 0.01 l 21 white everlasting Gnaphalium canescens ssp. microcephalum 20 / 5 30 0.01 l 22 golden yarrow Eriophyllum confertiflorum var. confertiflorum 20 / 5 40 0.01 l 23 bush monkeyflower Mimulus aurantiacus 20 / 5 31 0.01 r 24 *windmill pink Silene gallica 20 / 5 21 0.01 b 25 eucrypta Eucrypta chrysanthemifolia var. chrysanthemifolia / 15 0.01 r 26 long-stemmed buckwheat Eriogonum elongatum var. elongatum 20 / 5 17 0.01 r 27 laurel sumac Malosma laurina 3 / 3 29 0.01 l 28 ~ blue dicks Dichelostemma capitatum ssp. capitatum+ / 28 l 29 Bigelow's spike-moss Selaginella bigelovii 20 / 5 13 0.02 l 30 narrowleaf bedstraw Galium angustifolium ssp. angustifolium 10 / 3 39 l 31 common bedstraw Galium aparine 30 / 5 20 l 32 prickly cryptantha Cryptantha muricata / 13 l 33 coffee fern Pellaea andromedifolia 5 / 2 17 l 34 Robinson's pepper-grass Lepidium virginicum var. robinsonii 30 / 3 2 l 35 wild sweetpea Lathyrus vestitus var. vestitus 5 / 1 7 l 36 *common chickweed Stellaria media 30 / 5 16 l 37 California polypody Polypodium californicum 20 / 3 12 r 38 *castor bean Ricinus communis 20 / 5 12 l 39 small-flowered melica Melica imperfecta / 25 l 40 leafy daisy Erigeron foliosus var. foliosus / 29 l 41 *sow thistle Sonchus oleraceus / 21 l 42 scarlet larkspur Delphinium cardinale 5 / 1 3 l 43 bicolored everlasting Gnaphalium bicolor 10 / 3 20 l 44 southern Indian pink Silene laciniata ssp. major 10 / 2 11 l liverworts l 45 sp *rose clover Trifolium hirtum / 5 l 46 California everlasting Gnaphalium californicum 2 / 1 24 r 47 *petty spurge Euphorbia peplus / 6 l 48 ~ globe gilia Gilia capitata ssp. abrotanifolia 10 / 1 4 l 49 California chicory Rafinesquia californica / 14 0.07 Road turns right at drainage. Plants downhill are mostly weedy non-natives; plants uphill are mostly native. r 50 giant wild rye Leymus condensatus 5 / 1 22 l 51 California suncup Camissonia californica / 13 l 52 wild canterbury bells Phacelia minor / 12 l 53 chia Salvia columbariae 30 / 5 17 l 54 white sage Salvia apiana 20 / 5 27 l 55 *goldentop Lamarckia aurea / 11 l 56 California dodder Cuscuta californica var. californica / 12 l San Gabriel thrust fault exposed; look for bedrock on top of alluvium! l 57 *Spanish broom Spartium junceum 5 / 2 7 r 58 *narrowleaf filago Filago gallica / 29 l 59 *red brome Bromus madritensis ssp. rubens / 35 l 60 *hairy rattail fescue Vulpia myuros var. hirsuta / 9 l 61 *tocalote Centaurea melitensis 5 / 1 32 l 62 *common groundsel Senecio vulgaris 3 / 1 11 0.13 l Jct. Altadena Crest Trail r 63 Coulter's lupine Lupinus sparsiflorus 30 / 5 7 l 64 *Jerusalem oak Chenopodium botrys 5 / 1 3 l 65 chaparral yucca Yucca whipplei 3 / 3 20 l 66 San Bernardino sun-cup Camissonia confusa / 1 r 67 *giant reed Arundo donax 5 / 2 7 (bird's-foot fern, Pellaea mucronata var. mucronata) l 67 Vasey's prickly pear Opuntia Xvaseyi 1 / 1 15 l 68 ~ popcorn flower Cryptantha intermedia / 18 0.15 Beginning of bridge over Eaton Wash; elevation 1240 feet. b 69 white alder Alnus rhombifolia 3 / 1 9 0.16 End bridge l Check for Nevin's brickellia, Brickellia nevinii. 0.16 r Jct. Eaton Canyon Park Main Road; continue straight on Toll Road. l 70 California fuchsia Epilobium canum ssp. canum / 11 r 71 sp *Cypress sp. Cupressus sp.+ / 1 l 72 ssp thick-leaved yerba santa Eriodictyon crassifolium / 2 r 73 dwarf lupine Lupinus bicolor / 17 l 74 California poppy Eschscholzia californica / 20 l 75 creek senecio Senecio flaccidus var. douglasii / 9 l 76 *bermuda grass Cynodon dactylon / 15 l 77 collar lupine Lupinus truncatus / 16 r 78 *smooth cat's ear Hypochaeris glabra / 21 r 79 birch-leaf mountain-mahogany Cercocarpus betuloides var. betuloides / 14 r 80 annual sunflower Helianthus annuus / 8 r 81 sp *planted 3 needle (Jeffrey?) pine Pinus sp.+ / r 82 *Valley oak Quercus lobata+ / 1 1 r Large drain on ridgeline. r 83 *black locust Robinia pseudoacacia+ / 1 6 0.43 Cross drainage l Best field of Coulter's lupine, Lupinus sparsiflorus. r Road drain. l 84 pygmy-weed Crassula connata / 11 r Turnout. r 85 Acton's encelia Encelia actoni / 1 r Road drain. r Turnout. r 86 *Australian pine Casuarina equisetifolia+ / 1 r Sign with Bicycle Rules l 87 black sage Salvia mellifera / 29 r Road drain. r 88 *California burclover Medicago polymorpha / 26 l (Giant needlegrass, Achnatherum coronatum) l 89 white nightshade Solanum douglasii / 12 Cross weird drainage. l 90 red-gland spurge Chamaesyce melanadenia / 8 r 91 stinging lupine Lupinus hirsutissimus / 11 r Small drain. l 92 *fountain grass Pennisetum setaceum / 8 0.62 Cross drainage with interesting alcove / dry waterfall on left. l 93 hollyleaf redberry Rhamnus ilicifolia / 31 0.85 Cross large drainage with a flat-topped low retaining wall, good for sitting on. l 94 bittercress Cardamine oligosperma / 5 l 95 threadstem Pterostegia drymarioides / 14 l 96 narrow-leaved miner's lettuce Claytonia parviflora ssp. parviflora / 8 l 97 miner's lettuce Claytonia perfoliata ssp. perfoliata / 12 l 98 hollyleaf cherry Prunus ilicifolia ssp. ilicifolia / 9 l 99 heartleaf penstemon Keckiella cordifolia / 19 r 100 poison oak Toxicodendron diversilobum / 29 r 101 toyon Heteromeles arbutifolia / 35 l 102 goldback fern Pentagramma triangularis ssp. triangularis / 12 l 103 California lace fern Aspidotis californica / 4 l 104 woolly Indian paintbrush Castilleja foliolosa / 1 0.98 r Jct. Horse Trail down to lower Eaton Canyon; take it; elevation 1635 feet. l 105 south coast morning-glory Calystegia macrostegia ssp. intermedia / 12 l 106 sugar bush Rhus ovata / 19 r 107 ? the unknown ~agave mystery plant from sunset ridge l Firecracker Plantation, where the 1993 fire was started by a transient. l (Unk. pine tree, not P. halapensis) r 108 *olive Olea europaea / 8 r 109 saw-toothed goldenbush Hazardia squarrosa var. grindelioides / 26 l 110 Bigelow's coreopsis Coreopsis bigelovii / 1 r 111 San Gabriel Mtns. leather oak Quercus durata var. gabrielensis / 3 b 112 chamise Adenostoma fasciculatum / 27 r 113 *Russian thistle Salsola tragus / 22 r 114 bristly goldenaster Heterotheca sessiliflora ssp. echioides / 5 r (blue elderberry, Sambucus mexicana) l 115 ? Helianthus gracilentus? l 116 Engelmann leather oak hybrid Quercus durata var. gabrielensis X Q. engelmannii / 2 r 117 blue elderberry Sambucus mexicana / 34 r (Check for possible Quercus durata X Q. berberidifolia.) l 118 Southern California black walnut Juglans californica var. californica / 3 l 119 *blue gum Eucalyptus globulus / 4 r 120 California coffeeberry Rhamnus californica ssp. californica / 12 1.49 End guide at jct. with Main Eaton Canyon Road; elevation 1080 feet.
Comments On Specific Species Hordeum murinum. These are perfect ssp. leporinum in Munz, with 4.7 spikelets per cm of rachis, male lateral spikelets, and an inflorescence that is partially sheathed. However, they key to ssp. glaucum in JM, with the central floret slightly < lateral florets and the anthers of lateral florets ~2x anthers of central floret! The central lemma awn is slightly longer than the lateral lemma awns, not shorter, per the JM description.
Hence we have chosen to not give a subspecies here, and will accumulate further data from other locations to see how common this situation is.
Lotus scoparius var. brevialatus. The subspecies was determined from plants later on the trail; thus it is possible that this specimen is var. scoparius, since both varieties are found in the vicinity.
Dichelostemma capitatum ssp. capitatum. Only leaves were seen at this location, hence the ~ in the id? column. This taxon was found later on the trail.
Cupressus sp., Pinus sp., Quercus lobata, Robinia pseudoacacia, and Casuarina equisetifolia. The Sierra Club hikers who use this trail, in a well-intentioned by uninformed action, planted these species along the south side of the trail to eventually provide shade for hikers and bikers along this very unshaded route.
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Copyright © 2003-2006 by Jane Strong and Tom Chester.
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Comments and feedback: Jane Strong | Tom Chester
Updated 25 February 2006.