SENSITIVE AREA OF THE EASTERN SAN GABRIEL MOUNTAINS

Plateaus

“Glendora Brodiaea Reserve”
Glendora Community Conservancy
Los Angeles County
Glendora

by Dick Swinney
Copyright May 2005

Observations:
1988
May 1989
21 March 1990
20 April 1990
8 May 1990
19 May 1991
1 June 1991
8 June 1991
16 May 1992
8 May 1996
23 May 1996
1 May 2005
28 May 2007
Elevation: 1200 -1300 feet
Quad: Glendora
T 1N R 9W Section 20
Long. 117 deg. 50 min. 38 sec. W Lat. 34 deg. 9 min. 21 sec. N
Location: The plateau is approximately one-quarter mile north of the north terminus of Loraine Avenue in Glendora.
Description:
The 3.4 acre plateau is dissected steeply on portions of three of its flanks; the west, east and south. The north end of the plateau rises gently up a south-facing ridge of the San Gabriel Mountain foothills. The southern end of the plateau overlooks the coalesced alluvial fans of the Glendora basin.
The soil of the site is fine-grained, dark to red and of a clay consistency. This site was originally part of a 160 acre homestead occupied in the 1880’s. The plateau was first cleared in the early 1900’s by the Colby family, the owners of this property. Lemon orchards were planted on this site. The plateau was disked of weeds for fire abatement until May of 1988.The orchards declined until irrigation was halted in the early 1960’s.
Habitat: Disturbed site, naturalized grasses and weedy species surrounded by Coastal-Sage Scrub, Chaparral and Southern Oak Woodland.
Special Conditions: The property was last disked in May of 1988.

Name Abundance
1991 1992 2005

Dicotyledons
Achillea millefolium var. californica U None
Anagalus arvensis FC FC
Anthemis cotula U None
Anthriscus cacaulus None U (E. &W. margin)
Artemisia californica FC (N) C (N.)
Ascleplias fascicularis None 1 (S-E) None
Brassica rapa U None
Carduus pycnocephalus None FC (W.)
Centaurea melitensis A U ( S.-W.)
Centaurium venustum U None
Convolvulus sp? None U
Corethrogyne filaginifolia U U
Erodium cicutarium FC U
Erodium obtusiplicatum U None Euphorbia albamarginata FC None
Galium arvenis None U
Gnaphalium californicum None U
Hazardia squarrosus U 1 plant
Helianthus annuus C C
Hemizonia fasciculata U None
Hirshfeldia incana A U
Hordium leparinum U None
Hypochoeris glabra C U
Lactuca seriola seedlings abundant C C
Malacothrix saxatilis
var. tenuifolia U None
Marrubium vulgare FC 1 plant
Medicago lupulina None A
Phacelia cicutaria None U (margins)
Picris echioides U None
Quercus agrifolia 2 2
Rhaphanus sativus U U
Rumex crispus FC FC
Salvia mellifera None U (N.-E. margin)
Silybum marianum C (N-E) R C (N.-E.)
Solanum douglasii U U
Sonchus oleraceus U FC
Toxicodendron diversilobum FC FC (mostly in
margins)
Verbascum blattaria FC FC
Monocotyledons
Achnatherum pulchra U FC (S-E) C
Avena barbata A A
Brodiaea filifolia Expanding its
C range in S. section A
Bromus diandrus C C
Bromus madritensis A U
Bromus mollis A A
Hordium leparinum U None
Melica imperfecta U C ( mostly near margins)
Pennasetum setaceum None 1 clump (2 ft. X 2 ft)
(S.W.)
Piptatherum meliaceum U U
Vulpia myuros A R


The following plant species are currently encroaching on the margins of the plateau:
Epilobium canum
Eriogonum fasciculatum
ssp. foliolosum
Eriophyllum confertiflorum
var. confertiflorum
Juglans californicum
Melica imperfecta
Mimulus aurantiacus
Opuntia littoralis
var. littoralis
Salvia mellifera
Sambucus mexicana
Toxicodendron diversilobum

The following plant species are growing under two Quercus agrifolia trees on the plateau:
Heteromeles arbutifolia
Lonicera subspicata
Rhamnus ilicifolia
Rhus integrifolia

The six most common plants in order of their abundance as determined by casual observance:
1991 2005
1. Avena barbata 1. Avena barbata
2. Hirshfeldia incana 2. Bromus mollis
3. Bromus mollis 3. Medicago lupulina
4. Bromus madritensis 4. Brodiaea filifolia
5. Centaurea melitensis 5. Lotus soparius
6. Vulpia myuros 6. Bromus diandrus (in S-W area)
Naturalized species: 100% Naturalized species: 66%

Brodiaea filifolia Observations:
1988 Tye Garrison discovered the plants during an EIR for Everret Hughes. He counted 526 plants. From the number of plants blooming in relationship to the total number of plants he had growing at home, he estimated that the total population may be 800.
May 1989 Dick Swinney
total scapes counted: 230
March 21, 1990 Dick Swinney
total number of clumps of basal leaves counted: 660
clumps counted south of road: 622
clumps counted north of road: 38
All plants were in vegetative condition only. The surrounding herbacious species were not yet tall enough to obscure the view of the basal leaves of the Brodiaea. A total of 660 clumps of basal leaves were counted on the site. 38 plants were recorded north of the central east-west dirt road which runs through the site. 622 plants were counted south of the road. Plants were found growing near all margins of the plateau.
April 20, 1990 Orlando Mistretta and Melvin Crudge
They observed only a few plants in bloom
May 8, 1990 Dick Swinney
total scapes counted: 558
scapes counted south of road: 113
scapes counted north of road: 445
May 1990 Dick Swinney
870 scapes
May 19, 1991 Dick Swinney
total scapes counted: 961
scapes counted south of path: 706
scapes counted north of path: 255
The original road is no longer maintained and will be referred to as a path in all future reports as the encroaching vegetation has narrowed the width to less than two feet. Many scapes did not yet have blooming pedicels.
June 1, 1991 Dick Swinney
Floristic study was made to determine the percent of the population in bloom as in comparison to bud and fruit. The results showed that 55 percent of the flowers had completed blooming. The results can be found in the publication Glendora’s Brodiaea filifolia Past- Present - Future, Dick Swinney, June 1991
June 8, 1991 Dick Swinney
Floristic Study
Average number of pedicels per cape: 9
Average height of scapes: 34.9 cm.
Average maximum height of pedicel per scape: 5.3 cm.
Average number of pedicels in flower per scape: 1.2
May 16, 1992 Dick Swinney
1607 scapes
May 8, 1996 Dick Swinney
total scapes counted: 674
scapes counted south of the path: 393
scapes counted north of the path: 281
23 May 1996 Dick Swinney
total number of scapes counted: 425
25 May 1998 Dick Swinney
total number of scapes counted: 2,119
scapes counted south of the path: 1,681
scapes counted north of the path: 538
May 1, 2005 Dick Swinney
total scapes counted: 5,880
scapes counted south of path: 3,900
scapes counted north of path: 1,980
An attempt was made to count the scapes in bud only, as it represented a high percentage. Nearly all clusters(clumps) of Brodiaea had at least 40 % of scapes in bud only. Very few scapes were in fruit yet. A large percentage of plants this year were growing in very close clumps with 10 to 40 in a clump. Normally each scape is attached to a single bulb. This represents a very conservative count due to the high number of scapes in bud only. A significant number of scapes may not have even emerged at this date.
The distribution of the Brodiaea on the site has changed most significantly in the area south of the east-west path through the plateau. The density here is still greatest in the eastern area but is expanding significantly to the west. The significant increase in this population seems to be represented by a fairly consistent increase in all the
areas of original distribution except for that noted above.
May 28, 2007 Dick Swinney
total scapes counted: 22
scapes counted wsouth of path: 19
scapes counted north of path: 3
The number of peduncles with fruit verses with bud or flower was nearly equal. The population seems to be at their peak.
The 2006-2007 rainfall in Glendora was 4 to 7 inches. This represents the second driest year in southern California History.