Oakmead Herbarium: Additions and Changes to the Flora

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While native plants are occasionally documented, most recent additions to the flora are typically weeds and garden or agricultural escapes whose impact may not be known for years. The creeks are prominent avenues for plant introductions, as are roads and trails. Some of these pioneering plants naturalize and others not. Adventitious plants are usually not included on the main plant list before naturalization is confirmed. Among the former, notable introductions are Brachypodium sylvaticum (2007) via Sausal Cr., Euphorbia oblongata (2009) via Corte Madera Cr., and Ehrharta erecta  (2003) via Bear Cr. Change and succession in plant communities obviously brings floristic changes, gains, decline, and loss. We mention some declines and dissapearances below. In recent decades one observes woody plant (re)colonization of grassland, Eurasian annual grass adaptation to serpentinite, French broom and Acacia colonization of both larger creeks and other mesic habitats, and yellow star domination of large portions of the annual grassland, among other processes. During the past few years fresh eyes have also identified a bounty of native plants new to the Preserve.

Additional recent notable observations and vouchers: Floristic Postcards; Annual Report: Floristics

2024

• Salix sitchensis — SITKA WILLOW — Calflora | iNat Single, staminate tree
• Sanicula crassicaulis var. nudicaulis— Calflora | iNat Sinuate hairs on leaf margin. A NEW COMBINATION IN SANICULA CRASSICAULIS (APIACEAE). Madroño, 69(1):102-110 (2022). https://doi.org/10.3120/0024-9637-69.1.102
• Luzula comosa var. laxa COMMON WOOD RUSH, Redetermination based on Jepson eFlora
• Luzula macrantha (syn. Luzula comosa var. macrantha), Redetermination based on Jepson eFlora 
• Stephanomeria elata SANTA BARBARA STEPHANOMERIA — Flickr Calflora eFlora SPEC Chicory Tribe: 3-5 ft. tall annual; 7-15 pink ligulate flowers per head; outer phyllaries appressed proximally, spreading distally; tubercled cypselae angled longitudinally with long, narrow grooves on faces; pappus bristles wholly plumose. Gottleib (1972). Redetermination.

2023

• Isoetaceae — Isoetes nuttallii — Calflora, iNat [iNat record for discussion] 
• Isoetaceae — Isoetes howellii — Calflora, iNat [iNat record for discussion] 
• Orchidaceae — Piperia elongata — Calflora | iNat 
• Ranunculaceae— Ranunculus pusillus — Calflora 
• Juncaginaceae —Triglochin scilloides (Lilaea s.) — iNat, Calflora  — Semaphore grass depression (aka Pond A) and Boething marsh

2022

• Asteraceae — Hesperevax acaulis var. ambusticola  FIRE EVAX Calflora
• Caryophyllaceae  —  Polycarpon depressum CALIFORNIA POLYCARPON
• Convolvulaceae  —  Cuscuta campestris (syn. C. californica var. breviflora) FIELD DODDER. Redetermination
• Polemoniaceae  — Navarretia mellita 

2020-2021

• Asteraceae —Lessingia tenuis— Calflora — 2021, earlier vouchers annotated
• Asteraceae  —  Symphyotrichum subulatum parviflorum — 2021
• Boraginaceae   — Amsickia lunaris — 2021
• Fabaceae — Lotus tenuis — 2021
• Geraniaceae — Pelargonium grossularioides — 2020— adventitious
• Malvaceae — Malvella leprosa  Photo — 2020
• Oleacea  — Faxinus latifolia OREGON ASH — 2021
• Poaceae — Avena sativa — 2021 — adventitious, likely waif
• Poaceae — Phragmites australis— 2020 
• Poaceae — Sorghum bicolor — 2020 — adventitious, likely waif
• Polygonaceae  — Persicaria hydropiperoides WATER PEPPER— 2021 
• Pottiaceae —Hennediella stanfordiensis [moss]  — 2020
• Characeae — Chara sp. [freshwater green alga)  — 2020
• Aizoaceae — Sesuvium verrucosum  Photo — 2020

2019 and earlier

• Alismataceae — Sagittaria sanfordii  Photo  — 2019 [850 m downstream from the Preserve in San Francisquito Cr., by AEC consultants]
• Amaryllidaceae — Leucojum aestivum  Photo — photo by Alice Cumming 2/27/2018, Bear Creek at Preserve boundary fence; persisting
• Araceae — Arum italicum   Photo — photo by Brooke Fabricant 1/30/2018, east of bird count marker #5 off Leonard's Bridge. Also photo 2/27/2018, Bear Creek at Preserve boundary fence
• Asteraceae — Ancistrocarphus filagineus  Photo — 2019
• Asteraceae— Agoseris apargioides var. apargioides  COAST DANDELION, spec$, Not reported since 1873. Location Searsville; sheet annotated in 1953 and 1998
• Asteraceae — Dittrichia graveolens  STINKWORT   Photo — ongoing weeding. First appeared in 2005 in an area that was mowed to create a fire break and in a fire-staging area near the boundary of Portola Valley's Westridge neighborhood
• Asteraceae — Urospermum picroides  Photo — occasional in creeks
• Balsamiaceae  — Impatien balfourii  — single plant in San Franciscquito Creek, waif
• Brassicaceae  — Lepidium latifolium  BROADLEAVED PEPPERWEED  Photo — north bank of Bear Creek; so far limited
• Convolvulaceae — Cuscuta subinclusa  CANYON DODDER  Photo — previously reported but not vouchered  
• Euphorbiaceae — Euphorbia oblongata  OBLONG SPURGE  Photo  — new location, ongoing control effort 
• Fabaceae — Trifolium cernuum  NODDING CLOVER   Photo 
• Fabaceae — Ulex europaeus  GORSE   Photo — single plant removed 
• Fabaceae — Vicia villosa ssp varia Photo — spreading from historical range to ridgetop in 2016 
• Geraniaceae — Geranium purpureum Photo — speading in mesic habitats
• Geraniaceae — Geranium robertianum  Photo — likely present for sometime, conflated with Geranium purpureum
• Orobanchaceae — Parentucellia viscosa YELLOW GLANDWEED  Photo — controlled, but abundant on bordering SLAC
• Oxalidaceae — Oxalis corniculata  Photo  — previously reported but not vouchered  
• Oxalidaceae — Oxalis micrantha Photo — spreading 
• Rubiaceae — Galium parisiense — previously reported but not vouchered 
• Vitaceae — Parthenocissusquinquefolia  Photo — 2011 
• Alliaceae — Allium triquetrum  Photo — previously reported but not vouchered  
• Araceae — Wolffia aff. columbiana  WATERMEAL   Photo 
• Cyperaceae—Carex amplifolia  BIG-LEAF SEDGE   Photo — small population subsequently lost during winter flooding 
• Cyperaceae — Carex divulsa  GRAY SEDGE   Photo — Corte Madera Cr Delta, may not have naturalized 
• Cyperaceae — Carex gracilior  SLENDER SEDGE   Photo — locally rare, previously reported but not vouchered  
• Orchidaceae — Corallorhiza maculata var. occidentalis  SUMMER  CORALROOT   Photo — 2011, 2019 
• Poaceae — Brachypodium sylvaticum  SLENDER FALSE BROME  Photo — control effort 
• Poaceae — Ehrharta erecta  VELDT GRASS   Photo — spreading 
• Poaceae — Poa bulbosa   BULBOUS BLUEGRASS  Photo — plants removed, 2 locations

Arrival dates of some naturalized grasses

Some earlier non-graminoid arrivals

Disappearances and declines. Some plants (mostly annuals but also some perennials) have gone missing or persisit as a few individuals. Most are thought to have been present earlier in small local populations, some at the limit of their range, e.g., Actaea rubra, Adiantum aleuticum, Arabis blepharophylla, Viola ocellata. Dissapearance and decline in some cases can be attributed to specific flooding events, landslides, and human impacts, including management activities, particulary in the pre-Preserve period up to 1970s. Direct human impacts in the past 200 years include logging, land clearance, agriculture, sheep and cattle grazing and their removal, construction of the the reservoir and it's siltation, various other activities related to the Searsville Lake park and property adjacent to Sand Hill Rd, SLAC powerline right-of-way, and other infrastructure-related activities such as road and trail mantenance. Some workers have addressed larger environmental issues such as climate change or nitrogen deposition and soil fertilization.

And while some missing plants have undoubtedly winked-out, others, overlooked, have been refound (Lysimachia minima, Pentachaeta alsinoides, Triglochin scilloides), and others such as Athysanus pusillus and Myosurus minimus may still be present on the Preserve's almost 1200 acres. Others, disturbance or fire followers such as Antirrhinum kelloggii, Camissoniopsis micrantha, Chorizanthe diffusa, Malacothamnus fasciculatus, and Monolopia gracilens, are present nearby or in the seed bank.

1. Actaea rubra (BANEBERRY) Photo  — Relocated in 2019. First reported by Springer 1935 “in a shady place S end of lake”; Porter 1962: “Occasional in dense oak-madrone forest on north-facing slope above SF Cr.” Occasional in nearby in Windy Hill Open Space Preserve, San Francisquito Cr. watershed. 
2. Adiantum aleuticum (FIVE-FINGER FERN) Photo  — Collected 1965-1979. Scoured from rocks opposite W end of dam during El Nino of 1982-83; not reported since. A single location in Wunderlich County Park at slightly higher elevation, San Francisquito Cr. watershed.
3. Anthoxanthum occidentale (CALIFORNIA SWEET GRASS)  Photo  — Collected in 1867.
4. Antirrhinum kelloggii (LAX SNAPDRAGON)  Photo  — Collected in 1968 from seeds grown in a flat; seeds collected on ground in west-facing chaparral slope. Not reported since. Present in Edgwood Park and uncommon in Foothill Park, the latter in San Francisquito Cr. watershed.
5. Antirrhinum vexillocalyculatum ssp. vexillocalyculatum (WIRY SNAPDRAGON)  
6. Arabis blepharophylla (COAST ROCK CRESS) Photo — Collected 4/2/1984 Area H serpentine; no other reports.
7. Aralia californica (ELK CLOVER)  — First report by Zabel in 2001 Trail News a single plant growing in Corte Madera Cr floodplain; not observed since 2006. Present in Foothill Park, Phleger Estate, Huddart Co. Park, all in San Francisquito Cr. watershed.
8. Arnica discoidea (RAYLESS ARNICA) Photo   — Collected in 1921; Springer 1935: “Rare, oneplant on openly wooded slope and one at edge of chap.” Present in watershed.
9. Athysanus pusillus  — Collected in 2007
10. Boykinia occidentalis (COAST BOYKINIA)  Photo  — Relocated in 2021-2022. First reported in 1969
11. Camissoniopsis micrantha (MINATURE SUNCUP) Photo — Collected in 1972 (single plant in Rd E near big inlet); not reported since. Uncommon in Edgewood Preserve.
12. Castilleja foliolosa (WOOLLY PAINTBRUSH) —  Springer 1935: “Frequent on dry hillsides, especially in  rocky places”; Dengler 1975. Not reported since. Common in Hidden Villa near MROSD boundary.
13. Chorizanthe diffusa (DIFFUSE SPINEFLOWER) Photo collected in 1901 and 1910 “Dry rocky areas in chaparral and grassland.’ Locally abundant in MROSD Pulgas Ridge Preserve.
14. Cirsium brevistylum (CLUSTERED THISTLE)  Photo  Only occasionally seen; locally rare.
15. Cirsium occidentale var. occidentale COBWEBBY THISTLE )  Photo — Collected in 1974 and  1979 “Below dam near ‘old’ low-flow crossing”; not reported since.
16. Cirsium occidentale var. venustum (VENUS THISTLE)  Photo — Collected in 1963 “Oak woodland at Westridge end of ridge” and 1973 along Rd Dwest of Rd E; not reported since.
17. Corallorhiza maculata (SPOTTED CORALROOT)  Photo — Relocated in 2019. Uncommon, Trail 12; not observed since 2011. 
18. Crocanthemum scoparium scoparium  (Helianthemum scoparium) — Relocated in 2022.  Most lost in 4th year of drought 2015-2016. Earliest record 1898 (JROH1831).
19. Cuscuta campestris (C. californica var. breviflora) — Relocated.  Searsville Lab Landing; host Xanthium strumarium; corolla with scales. (There are local records for C. campestris on Xanthium, including Felt Lake, Lake Lagunita and Crystal Springs area)
20. Delphinium variegatum ssp. variegatum (ROYAL LARKSPUR) — Collected 1954-1980 in serpentine grassland on NW part of Ridge; not reported since. Springer 1935 “Infrequent.”
21. Epilobium torreyi (TORREY’S WILLOWHERB)  Photo — Relocated in 2019. Collected 1961-1969, locally common in two locations in oak woodland.
22. Juncus bolanderi (BOLANDER'S RUSH) Photo — Collected along bank of Corte Madera Cr. in 1977; not seen since 2004. 
23. Leptosiphon liniflorus (FLAX-FLOWERED LEPTOSIPHON) Photo — Collected in 1895 “near Searsville”; not reported since. Present along Edgewood Trail in serpentine.
24. Linanthus dichotomus (EVENING SNOW) Photo — Collected from 1896-1920 on “ridge”; not reported since.
25. Lupinus microcarpus var. densiflorus (CHICK LUPINE) — Springer 1935: “abundant in a single location on grassy hillside in ravine”; Dengler [Notebook] 11/11/62 “to 2 in. above cotyledon leaves above fence C.M.F.” No recent reports. Common off Edgewood Rd at Edgewood Park border; Deer Creek Conservation Area, Stanford U.
26. Lysimachia minima [Anagallis m.; Centunculus minimus] (CHAFFWEED) Photo — Relocated in 2024. Collected 1962-1981 “Grassy meadows in [blue] oak woodland” and “Low wet areas in grasslands.” Relocated in 2024.
27. Malacothamnus fasciculatus (CHAPARRAL MALLOW) Photo — Relocated in 2024. Springer in 1935 reported Sphaeralcea arcuata “infrequent” but evidently more widespread than at present. A single shrub persisted as of 6/2013. Common on city property along the Westridge fenceline. Present at Edgweood Preserve, population reinvigorated by fire.
28. Monolopia gracilens (WOODLAND WOOLLYTHREADS) Photo — Collected in 1971; not reported since. Report by Springer 1935 “Abundant in one place—near edge of chaparral above the lake”; Dengler [Notebook] 5/12/63 “at site on end of "road" to above G.C (coll & pressed) None found in former locations, but just over edge of Canyon at edge of chap but still in grass. Few, but all from 12 in to 18 in.” Present at Edgweood Preserve.
29. Myosurus minimus. Collected in 1981; not reported since.
30. Nemophila menziesii var. menziesii. Declining
31. Oxalis oregana (REDWOOD SORREL)  Photo  — Collected in 1915.
32. Pentachaeta alsinoides (TINY CHAETOPAPPA)  Photo — Relocated in 2022. Fairly common on the ridge top in 1958; most recent report 1989.
33. Petunia parviflora (WILD PETUNIA) Photo — Collected in 1909 “Searsville Lake”; not reported since.
34. Pickeringia montana ssp. montana (CHAPARRAL PEA)  — Declining
35. Platystemon californicus (CREAM CUPS) Photo  — Not observed since April, 2002. Earliest report by Moeur in 1947: “infrequent in moist meadows and along roadsides in February and March.”
36. Ranunculus aquatilis var. diffusus — May, 1981, Dengler: "by trail at small pond in the Nolan Creek delta area"; not reported since. Petals white; both floating and submersed lvs w/ linear segments
37. Scoliopus bigelovii (SLINK POD)  Photo — Collected in 1867.
38. Triglochin scilloides (FLOWERING-QUILLWORT)  Photo — Relocated in 2023. Dengler 1975; Herbarium 2005: “near preserve boundary at former Boething Nursery site.”
39. Triodanis biflora (SMALL VENUS LOOKING-GLASS) Photo — Relocated in 2022. Collected in 1921 and 1979 “NW end of Searsville Lake”. Reported by Springer 1935: “one place–open spot between chaparral and wooded slope at top of hill above lake in May.”  Uncommon in Edgewood Preserve.
40. Triphysaria eriantha ssp. eriantha (BUTTER-AND-EGGS) Photo  — Collected in 1896 “Searsville Ridge”; not reported since.
41. Tropidocarpum gracile (LACEPOD) Photo — Collected in 1972 and 1977 “Near poppy knoll”; not reported since. First reported by Springer 1935: “Frequent on open hillsides.”
42. Viola ocellata (WESTERN HEART'S EASE) Photo — Collected in 1893 and 1972 near Tiger Lily site Trail 1; not reported since. 

 Hybrids without taxon entry in Jepson eFlora

SPEC—Specimen, at the Jasper Ridge herbarium (JROH). Plant presumed present unless otherwise noted. 
DOC—Documented, plant observed and/or photographed by herbarium team but not vouchered. REP—Reported. 

• Castilleja attenuata x Castilleja densiflora — DOC (JROH5780) — Infrequent. Not currently included on the main plant list
• Castilleja densiflora x Castilleja rubicundula ssp. lithospermoides  Photo — SPEC (JROH4012, 5852, DS727348) — Occasional.
• Elymus x hansenii (Elymus glaucus x Elymus multisetus)  Photo — SPEC — Short-lived perennials.
• xSchedololium loliaceum (Huds.) Holub (Festuca arundinacea x Festuca perennis)  Photo — SPEC (JROH5172, 5173) — Branched Lolium. 
• Lupinus microcarpus var. densiflorus X L. nanus — REP  —  Dengler [Notebook] 4/14/63 “Lupinus nanus x L. densiflorus–upper C.M.F.in bloom on hip of hill above fence particularly 50 ft. up. These L. nanus seem introgressed, but pods must be gathered Leaflets too broad for L. nanus and flowers more verticillate. Pods beginning, but already secund.” Not currently included on the main plant list
• Primula clevelandii x P. hendersonii hybrids have been reported by Herb Dengler in 1959 and 1973 (JROH3384, 3386 respectively). Individuals not exactly matching taxa described in different manuals (Munz, Thomas, TJM) have been referred to either Primula clevelandii var. patula or P. hendersonii following TJM2; further examination of this material is desirable. Dodecatheon confusion is not unique to our locality. Not currently included on the main plant list
• Quercus agrifolia var. a. x Q.  parvula? — REP— Dengler, 1975 Plant List; SPEC 2020; A single tree 20 m tall on trail 11
• Quercus douglasii x Q. durata  Photo — SPEC (JROH2538, UCD46005) — JR oaks and hybrid oaks; John Tucker (1992) letter. 
• Quercus x chasei (Quercus agrifolia var. a. x Q. kelloggii )  Photo — SPEC — Zabel (2003) JR oaks and hybrid oaks. 
• Quercus x  jolonensis (Quercus douglasii x Q. lobata )  Photo — SPEC — Zabel (2003) JR oaks and hybrid oaks. 
• Quercus x morehus (Quercus wislizeni var. frutescens x Q. kelloggii) — SPEC —  JROH2534 collected 3/19/1898 as Quercus; annotated Quercus x morehus by John Thomas in 1958. No known current locations.

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