Plant Guide to Colby Trail, Glendora, 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

Highlights of This Trail
Plant Communities and Floristics
Fieldwork Dates and Summary of List Changes With Time
The Plant Guide
Comments On Specific Species


Directions to the trailhead:
From SR57 North:
Take the Auto Centre Drive exit, just before SR57 turns into the I-210. Then left to Lone Hill Avenue, left on US66 (Alosta Avenue) to Loraine Avenue, then right on Loraine to its northern end.
From I-210 East: Take the Grand Avenue exit. Turn left and head north to Sierra Madre Avenue, then right to Loraine Avenue. Turn left on Loraine to its northern end.

There is parking for ~five cars on the cul-de-sac at the end of Loraine, but the street is signed no parking below the cul-de-sac at its end.

Thomas Brothers L.A. County map 569, G3.

Highlights of This Trail

This trail is riparian in its lower stretch, with specimens of some species much larger than normal. It contains a vernally moist area, possibly with a vernal pool in wet years, as well as a flattish area with native grasslands that includes the ENDANGERED Brodiaea filifolia. The Jepson Manual says that this species is extirpated from Los Angeles County, but this area is proof that at least a small pocket of these plants survives here.

The upper portion of the trail is fairly typical low elevation San Gabriel Mountains chaparral, but there are patches of volcanic rock, very unusual in the foothills of the San Gabriel Mountains. These Glendora Volcanics are of middle Miocene age (~13 million years ago), roughly the time when the San Andreas Fault first became active. The volcanic rocks are composed of andesitic flows, flow-breccias, tuff-breccias and tuffs (mapped by Shelton, 1955, Geol. Soc. American Bull. 66: 45-90). It probably isn't an accident that these volcanic rocks were deposited along the fault at the foot of the San Gabriel Mountains here, since that was the ancestral San Andreas Fault before it jumped to the northern base of the mountains. (Source: Geology and Mineral Wealth of the California Transverse Ranges, South Coast Geological Society, 1982.)

It is interesting that the only two locations we have found Brodiaea filifolia on our 74 trail lists so far both have similar volcanic rock of roughly the same age. (The other location is the Vernal Pool Trail on the basalt of the Santa Rosa Plateau Ecological Reserve.)

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 74 trails in our database when this histogram was made. This is the only trail in Glendora, but we have a number of trails along the south edge of the San Gabriel Mountains. A number of "1" means the taxon has only been found on this trail among the trails in our database.

Number of Trails
Containing A Taxon
Number Of Taxa
On This Trail
% of Taxa
On This Trail
Total Taxa101100%

We found one additional species not in the above table, since it has not been identified yet, the Cuscuta sp. below, marked with sp in the id? column in the guide, and without an entry in the #all column.

The taxa that are unique, or almost unique, to this trail or area, out of our 74 trails on 11 May 2004, are:


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 DateVisit ## taxa# "?"# "sp"# "~"# "ssp"

We thank Bob Muns, and two other people for their help with the fieldwork on 4/22/04. We thank one of those people with pointing out the interesting volcanics on this trail!

In addition, Michael Charters found the Phacelia minor and Brassica rapa on 2/23/05.

The Plant Guide

Version for printing, without lines and other text on this page (4 pages)

Miles#id?Common NameLatin Name#here#all
0.00   Begin trail at the northern end of Loraine Avenue in Glendora.
0.00c1 *white goosefootChenopodium album / 13
0.00b2 *foxtail barleyHordeum murinum ssp. glaucum / 7
0.00l3 *ripgut bromeBromus diandrus / 37
0.00l4 common bedstrawGalium aparine / 23
0.00r5 *horehoundMarrubium vulgare / 21
0.00r6 *prickly lettuceLactuca serriola / 23
0.00r7~*knotweedPolygonum arenastrum / 9
0.00r8 *Bermuda grassCynodon dactylon / 18
0.00l  (chaparral yucca, Yucca whipplei)
0.00l9~Engelmann leather oak hybridQuercus engelmannii X Q. durata var. gabrielensis / 3
0.00l10 Vasey's prickly-pearOpuntia vaseyi / 17
0.00l11 *Russian thistleSalsola tragus / 23
0.00l12 coast live oakQuercus agrifolia var. agrifolia / 32
0.00l13 *cheeseweedMalva parviflora / 13
0.00c14 *redstem filareeErodium cicutarium / 39
0.00r15 *wild oatsAvena fatua / 15
0.00r16 *sow thistleSonchus oleraceus / 24
0.01l  Kiosk and shaded benches
0.01r17 *Bermuda buttercupOxalis pes-caprae / 6
 r18 *smilo grassPiptatherum miliaceum / 17
 r19 laurel sumacMalosma laurina / 30
 l  Signpost: "Poison oak [territory?]"
 l20 branching phaceliaPhacelia ramosissima var. latifolia / 26
 l21 white nightshadeSolanum douglasii / 14
 l22 poison oakToxicodendron diversilobum / 32
 l23 blue elderberrySambucus mexicana / 36
 l24 south coast morning-gloryCalystegia macrostegia ssp. intermedia / 14
 r25 sacred daturaDatura wrightii / 14
 l26 wild-cucumberMarah macrocarpus var. macrocarpus / 36
 r27 western sycamorePlatanus racemosa / 18
 r28 *petty spurgeEuphorbia peplus / 8
0.04r29 Southern California black walnutJuglans californica var. californica / 4
 l30 small-flowered melicaMelica imperfecta / 30
 l31 heartleaf penstemonKeckiella cordifolia / 20
 l32 toyonHeteromeles arbutifolia / 36
 r33~*Mexican Fan PalmWashingtonia robusta+ / 2
 r  (passion flower, Passiflora caerulea)
 l34 virgin's bowerClematis ligusticifolia+ / 6
0.08l35 *hedge mustardSisymbrium officinale / 13
 l36 California brickellbushBrickellia californica / 24
 r37 *Italian thistleCarduus pycnocephalus / 11
 l38 *California burcloverMedicago polymorpha / 27
 l39 *bur chervilAnthriscus caucalis / 7
 r40 *passion flowerPassiflora caerulea / 1
 r41 pellitoryParietaria hespera var. hespera / 4
 r42 hillside gooseberryRibes californicum var. hesperium / 5
 l43sp3 needle pinePinus sp. /  
 l44 southern honeysuckleLonicera subspicata var. denudata / 31
 l45 basketbushRhus trilobata / 15
 r46 California everlastingGnaphalium californicum / 27
 l47 *tocaloteCentaurea melitensis / 33
 l48 *scarlet pimpernelAnagallis arvensis / 17
 l49 *shortpod mustardHirschfeldia incana / 39
 l  Troop 486 Eagle Scout Project for erosion control.
 l50 *milk thistleSilybum marianum / 9
 l51 white sageSalvia apiana+ / 29
 l52 California fuchsiaEpilobium canum ssp. canum+ / 12
 l53sspCalifornia buckwheatEriogonum fasciculatum var. foliolosum+ / 39
 l54 *slender wild oatsAvena barbata / 24
 l  (small-seeded spurge, Chamaesyce polycarpa)
 l55 California sagebrushArtemisia californica / 33
 l56 white everlastingGnaphalium canescens ssp. microcephalum / 31
 l57 long-stemmed buckwheatEriogonum elongatum var. elongatum / 18
 l  (short-leaved cliff-aster, Malacothrix saxatilis var. tenuifolia)
 l58 California four o'clockMirabilis californica / 15
 l59 chaparral yuccaYucca whipplei / 22
0.14l60 *purple false-bromeBrachypodium distachyon / 4
 l61 bush monkeyflowerMimulus aurantiacus / 32
 l62spdodderCuscuta sp. / 2
 l63 narrowleaf bedstrawGalium angustifolium ssp. angustifolium / 41
 r64 hollyleaf redberryRhamnus ilicifolia / 32
0.16l65 deerweedLotus scoparius var. scoparius+ / 21
 l66 golden yarrowEriophyllum confertiflorum var. confertiflorum / 43
 l67 long-leaf bush lupineLupinus longifolius / 3
 r68 wild sweetpeaLathyrus vestitus var. vestitus / 8
 r69 San Gabriel Mtns. leather oakQuercus durata var. gabrielensis / 4
0.18l70 short-leaved cliff-asterMalacothrix saxatilis var. tenuifolia / 10
0.20r  Jct. road; sign: "[left] To gate 1.0 mile; [right] To berm 0.4 mile"; continue straight
0.22l  Jct. path; go left on it.
0.23r71 annual sunflowerHelianthus annuus / 9
0.23r72sp*wand mulleinVerbascum virgatum / 3
0.23r73 *curly dockRumex crispus / 14
0.23r74 purple needlegrassNassella pulchra / 10
0.24   Trail is immediately to left of gate with fence only to the right of the gate.
0.24l75 thread-leaved brodiaeaBrodiaea filifolia / 2
0.24l76 *prickly sow thistleSonchus asper ssp. asper / 15
0.24r77 *field bindweedConvolvulus arvensis / 2
0.26l78 *white-stemmed filareeErodium moschatum / 12
0.26r  (fountain grass, Pennisetum setaceum)
0.27 79 *red bromeBromus madritensis ssp. rubens / 39
0.27   Turn-around, but then head to the east off-trail for more Brodiaea and the lemonade berry.
0.31 80 lemonade berryRhus integrifolia+ / 12
0.34   Back on the main road; go right, back down trail.
0.36   Back at the jct. with the road to the berm; go left and take it.
0.39l81 *purple wild radishRaphanus sativus / 10
0.40r  (California buckeye, Aesculus californica)
0.41 82 California black oakQuercus kelloggii / 11
0.44   Road goes up short steep hill.
0.47b83 *castor beanRicinus communis / 13
0.47l  (wall bedstraw, Galium parisiense)
0.48   Road ends at the top of the hill and the berm; return to the road junction.
0.60   Back at the road jct; go right, uphill.
0.62l84 *goldentopLamarckia aurea / 12
0.66   Trail curves right 90°
0.67l85 *tree tobaccoNicotiana glauca / 17
0.69r86 *Peruvian pepper treeSchinus molle / 5
0.71 87 caterpillar phaceliaPhacelia cicutaria var. hispida / 9
0.75 88 California buckwheatEriogonum fasciculatum var. polifolium / 12
0.76l89 nodding needlegrassNassella cernua / 8
 l  (giant wild-rye, Leymus condensatus)
0.81r90 *common beggar-ticksBidens pilosa var. pilosa / 3
0.82l  lemonade berryRhus integrifolia+ /  
0.82r91 mugwortArtemisia douglasiana / 24
0.83r92 telegraph weedHeterotheca grandiflora / 23
0.86l  (chamise, Adenostoma fasciculatum)
0.87l  A yellow bush monkeyflower, Mimulus aurantiacus, immediately next to a red bush monkeyflower. Maybe this is why the Jepson Manual combined the two formerly-separate species into one!
0.89r  Jct. path (with more Brodiaea?); Trail turns left 90° and steepens.
0.90r93 black sageSalvia mellifera / 32
0.90l94ssp*rattail fescueVulpia myuros / 6
0.96   Trail curves right 90°
0.96r95 gray sageSalvia apiana X S. mellifera / 3
0.97r  (coffee fern, Pellaea andromedifolia)
0.97r96 blue dicksDichelostemma capitatum ssp. capitatum / 31
0.98r  (California peony, Paeonia californica)
0.99l97 purple clarkiaClarkia purpurea ssp. quadrivulnera / 13
0.99r  (creek senecio, Senecio flaccidus var. douglasii)
1.00r  (lanceleaf dudleya, Dudleya lanceolata)
1.02r  (bicolored everlasting, Gnaphalium bicolor)
1.03r98 rattlesnake weedChamaesyce albomarginata / 2
1.04b99 *winter vetchVicia villosa ssp. varia / 11
1.04b100 *smooth cat's earHypochaeris glabra / 22
1.05l101~bristly goldenasterHeterotheca sessiliflora ssp. echioides / 6
1.06l102 *alfalfaMedicago sativa / 2
1.08   Jct. Glendora Mountain Road; end guide.

Comments On Specific Species

Washingtonia robusta. Location not precise.

Clematis ligusticifolia. The identification was from blooming plants located just off-trail a short distance farther along the trail.

Salvia apiana, Epilobium canum ssp. canum, Eriogonum fasciculatum var. foliolosum. The first three specimens on the trail were planted by the Boy Scouts, but each species is found naturally a short distance up the trail.

Lotus scoparius var. scoparius. The identification of the subspecies was from plants blooming near the Brodiaea filifolia.

Rhus integrifolia. The first noted specimen is off-trail near the other plants of Brodiaea filifolia; the first specimen along the trail is also noted, but not numbered.

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Copyright © 2004 by Jane Strong and Tom Chester.
Permission is freely granted to reproduce any or all of this page as long as credit is given to us at this source:
Comments and feedback: Jane Strong | Tom Chester
Updated 24 February 2005.