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

2022

2020-2021

2019 and earlier

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 (perhaps Lysimachia minima, Myosurus minimusPentachaeta alsinoides, Triglochin scilloides, 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, perhaps are present in the seed bank.


 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. REPReported. 

  • Castilleja attenuata x Castilleja densiflora — DOC (JROH5780) — Infrequent. Not currently included on the main plant list
  • Castilleja densiflora x Castilleja rubicundula ssp. lithospermoides camera icon Photo — SPEC (JROH4012, 5852, DS727348) — Occasional.
  • Elymus hansenii (Elymus glaucus x Elymus multisetuscamera icon Photo — SPEC — Short-lived perennials.
  • xSchedololium loliaceum (Huds.) Holub (Festuca arundinacea x Festuca perennis) camera icon 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 clevelandiiP. 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 camera icon Photo — SPEC (JROH2538, UCD46005) — JR oaks and hybrid oaks; John Tucker (1992) letter
  • Quercus x chasei (Quercus agrifolia var. a. x Q. kelloggii camera icon Photo — SPEC — Zabel (2003) JR oaks and hybrid oaks
  • Quercus x  jolonensis (Quercus douglasii x Q. lobata ) camera icon Photo — SPEC — Zabel (2003) JR oaks and hybrid oaks
  • Quercus x morehus (Quercus wislizeni var. frutescens 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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