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University and Jepson Herbaria - UC Berkeley

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University and Jepson Herbaria - UC Berkeley

The UC Berkeley Herbaria promote botanical research, education, training, and conservation in California and worldwide.

09/04/2026

One Saturday of each month, there is a Group Volunteer Day in the Herbaria! We hope to welcome back participants from previous years and greet a diversity of new faces. Our focus will be chipping away at the unmounted backlog of pressed plant collections, from California and around the world, some brand new, some decades old. Expect a diversity of "buried treasures" to come to light, primarily new records of noteworthy plants. Volunteers are greatly needed to mount, sort and file these collections. As well, assist with any other related projects. No previous herbarium experience is necessary but a level of dexterity and attention to detail is valued.

Spring 2026 volunteer dates are: September 26, October 17, November 14, and December 12. Group Volunteer Saturday begins at 10:00 a.m. and finishes up by 4:00 p.m. (participants don’t need to stay the full time).

Please let us know you're coming! Email Saskia Raether ([email protected]).

The University and Jepson Herbaria are in the Valley Life Science Building on the campus of the University of California at Berkeley. The entrance is on the ground floor of the atrium, in front of the Tyrannosaurus rex. The central Berkeley BART station is convenient, as are numerous bus lines. Free parking can generally be found along the streets north of campus.

08/23/2026

Happy Seaweed Sunday! This month let’s snorkel in the Caribbean to find an umbrella-shaped green alga called Acetabularia. This seaweed grows in protected, shallow water on tropical to subtropical shores throughout the world. The thallus of Acetabularia is a single, large cell composed of rhizoids at the base, a stalk, and a cap at the apex. The cell walls of Acetabularia may be lightly to heavily calcified, giving the seaweed a milky green appearance and structural support to keep the stalk and cap upright to gather sunlight.

As a juvenile, the thallus first develops the rhizoid and then a slim stalk, upon which it periodically produces whorls of finely branched hairs. These hairs eventually fall off, leaving behind scars on the stalk surface. After reaching a species-specific length, the stalk apex forms a whorl of branches called cap rays (or gametophores), which adhere to each other to form the umbrella-like cap.

Unlike other siphonous greens, which are multinucleate throughout the vegetative phase, Acetabularia has a single, large diploid nucleus located in the rhizoid. Once the cap is formed, the nucleus undergoes meiosis followed by mitosis to form many haploid secondary nuclei that migrate up the stalk and into the gametophores. Once in the ray, a thick wall surrounds each nucleus, resulting in many round cysts. Inside the cysts, the nuclei divide again multiple times, each eventually forming a gamete. The gametes are released and fuse to create zygotes that develop into juveniles.

Acetabularia evolved around 38 million years ago; large fossil deposits have been found from around 12 mya in present-day Romania.

This species has co-evolved with the sacoglossan sea slug Elysia timida, which pierces and sucks the alga’s cytoplasm, retaining its chloroplasts. This gives the slug a distinctive green color and the ability to photosynthesize.

08/17/2026

It’s Moss Monday! This series uses “moss” as a broad term to cover all three bryophyte groups, including liverworts and hornworts in addition to mosses.

This month we’ll feature the beautiful moss Alsia californica. This lineage is endemic to the west coast of North America, occurring from the Channel Islands in southern California northward along the mainland coast from Pt. Conception to southern British Columbia. It is very common on trees in the Bay Area, and being a large, plumose moss it is easy to identify in the field. It is most similar to Dendroalsia californica but that moss (covered in an earlier post in this series) is more dendroid and curves down on the tree when dry, while Alsia curves up. Alsia also has spectacularly long, differentiated perichaetial leaves around its sporophytes.

Alsia is on an isolated evolutionary branch with no close relatives, which some rank as a monotypic genus, while others lump into a larger genus as Neckera californica. This illustrates a major limitation of the binomial system of nomenclature, when the name of a lineage is forced to change even though its circumscription has not. This has led to much frustration across California botany in general. I predict that eventually the solution will be to name all phylogenetic levels of taxa with unranked uninomials. This is quite controversial, of course; there is an abundant literature on species concepts and the PhyloCode to consult. My freely downloadable book “What, if anything, are species” discusses these issues in detail (https://www.taylorfrancis.com/books/oa-mono/10.1201/9781315119687/anything-species-brent-mishler).

- Brent Mishler, Curator of Bryophytes, UC/JEPS

08/15/2026

Welcome to another summer addition of ! How apropos that we are describing lichens from the beach!

Specifically, from rocks on the beach. Meet two lichens that specialize in growing on rocks in the upper rocky intertidal. Flavoplaca marina (formerly Caloplaca marina) has a widespread distribution, and often has a wide halo of prothallus around it. A prothallus is an initial mat of fungal hyphae that extends outwards, upon which the lichen thallus develops. Polycauliona rosei (formerly Caloplaca rosei) is primarily found on the west coast of North America, with a narrower, sometimes yellowish prothallus. Polycauliona rosei is characterized by a deep orange color with convex apothecia and a continuous to areolate thallus. Note that in the images, because it is growing on concrete, it has a more patchy growth pattern, and tends to grow primarily in the areas between the aggregate.

Both of these orange crustose lichens have to deal with intertidal conditions including salty sea spray and long term exposure to UV as there is minimal shade available. Here in the Lichen Lab at the University Herbarium, we are continuing to investigate the mechanisms these lichens use to adapt to coastal conditions.

08/07/2026

The Hawaiian Islands have a great diversity of ferns in the genus Asplenium, known for complex patterns of polyploidy, hybridization and high degrees of morphological variation. Asplenium macraei is a lovely and variable member of the Hawaiian Flora, known as `iwa`iwa lau li`i. Although previously considered endemic to the Hawaiian Islands, similar plants have been collected in Samoa and in the Marquesas – additional study is needed! Happy !

07/28/2026

New Jepson video posted! 💫

The Jepson Videos are short instructional videos focused on the plants of California. Focused on commonly encountered families and genera, the videos provide details on ecology and the characters used in identification. They are a great study aide for anyone learning about the California flora!

This month, join us for a dive into the mistletoes, in the family Viscaceae. These parasitic plants grow on the above ground parts of woody plants all over California where they feed and house birds, playing an important role in the ecosystem. All three genera of mistletoes found in California are covered here.
https://www.youtube.com/watch?v=-i_NjtIGCxc

Last month, we highlighted the genus Chlorogalum. Keep your eyes out in the coming months for videos about poison oak, Cornus, Phacelia, Pinus lambertiana, Pectis and Silene. To be notified when new videos are released, subscribe to our YouTube channel ()!

07/27/2026

It’s Moss Monday! This series uses “moss” as a broad term to cover all three bryophyte groups, including liverworts and hornworts in addition to mosses.

This month we’ll feature the moss Sphagnum mendocinum, which is endemic to western North America. It occurs from the north coast region of California up through southern Alaska. It is an notable part of the vegetation in its namesake locality, Mendocino County, particularly in the “ecological staircase” of old seashore terraces where the pygmy forest occurs. Sphagnum is not nearly as common in California as it is farther north in the boreal regions, where it is everywhere. There it is an ecological dominant that modifies the environment where it grows due to its water-holding capacity that can raise the water table, while acidifying the environment. But there are several species in the Sierra Nevada and northwestern California found in wet meadows and pond margins.

Sphagnum descends from an ancient phylogenetic split within the mosses; it diverged from the rest of the mosses some 400 million years ago. It has a bizarre morphology with two types of leaf cells: small green photosynthetic cells and large, clear water-holding cells. The latter cells are dead at maturity, have various type of reinforcing thickenings, and pores communicating with the outside -- allowing the plants to hold water like a sponge!

- Brent Mishler, Curator of Bryophytes, UC/JEPS

07/24/2026

The Jepson workshop program took its annual trip to the White Mountains this past weekend! 🏔️

The White Mountains are located at the southwest corner of the Great Basin floristic region, and their geologic and habitat diversity, high relief (spanning 3,950-14,246 feet elevation), and proximity to the Sierra Nevada and Mojave Desert all contribute to an unusually rich and well-documented flora of over 1,100 taxa. They are also known for the oldest living trees, the highest point in Nevada, and the third highest peak in California. July is typically peak blooming time for the subalpine and alpine floras.

Through driving tours and hikes, participants had the opportunity to explore the southern half of the White Mountains, observing and identifying diverse plants and learning to recognize various geologic and ecologic settings that influence species distributions and adaptations. We started in Bishop, moving up the elevation gradient to our weekend base station at Crooked Creek. We visited wetland and upland sites in various geologic settings at elevations up to about 12,000 feet.

Thank you to everyone who joined us for this fantastic workshop, and thank you to Jim Morefield and Dylan Neubauer for their continued involvement in the Jepson workshop program!

Check out the iNaturalist project to get a peek at what we observed during this workshop!
https://www.inaturalist.org/projects/white-mountains-workshop-2026

07/19/2026

Welcome back to !

Today I would like to re-introduce you to a crustose lichen that you have probably encountered before. Meet Rhizocarpon geographicum, the map lichen. This is a yellow and black crustose lichen that grows on rocks in a variety of habitats, but is best known from alpine environments. It has a cosmopolitan distribution.

Rhizocarpon geographicum uses a variety of mechanisms, including pigments, in order to survive in the harsh alpine tundra environment, where it is exposed to UV radiation, wind, warm summers and freezing winters. This lichen’s resilience has been put to the test through a number of simulations of and exposure to conditions of outer space! Though damaged, it survived, and was able to continue growing once returned to “earth conditions.”

I appreciate Rhizocarpon geographicum for the beautiful patterns it creates, both within a single thallus (body of an individual lichen) as well as the patterns created when multiple lichens grow on the same rock.

07/13/2026

Happy Seaweed Sunday! Let’s go diving along the Pacific coast and swim to a long, luxuriant brown seaweed called Stephanocystis, or the chain bladder kelp. Although they are large brown seaweeds, they are not kelps (order Laminariales). They are in the order Fucales, characterized by apical growth, a diplontic life cycle with oogamous reproduction, and gametangia borne in specialized pits called conceptacles. Stephanocystis species occur in the northern Pacific Ocean (four grow in California). The related genera Cystoseira and Halidrys occur in the Atlantic Ocean.

Stephanocystis thalli are dark to yellowish brown with discoid holdfasts, thick, woody stipes, and distinct lower and upper branching regions. The lower portion of the thallus includes the stipe, which is perennial and produces flattened branches that drop off in the winter. In the spring the stipe regenerates new branches as well as the annual upper portion, composed of cylindrical branches that bear small air bladders (pneumatocysts) that keep the thallus afloat. At maturity, the tips of these branches swell slightly to produce a fertile region (receptacle) bearing conceptacles, pits in which gametangia produce either s***m or egg cells.

One common species in California, S. osmundacea, forms dense stands in giant kelp forests, thus contributing to high primary productivity, habitat, and protection from predators for many fish and invertebrates. It also hosts epiphytic algae. Fossils from southern California, dating from the Miocene Epoch (25-5 million years ago), strongly resemble contemporary Stepanocystis species, and are among the rarest of seaweed fossils.

Address

1001 Valley Life Sciences Bldg
Berkeley, CA
94720

Opening Hours

Monday	8am - 5pm
Tuesday	8am - 5pm
Wednesday	8am - 5pm
Thursday	8am - 5pm
Friday	8am - 5pm

Telephone

(510) 643-7008

Website

http://linktr.ee/ucjepsonherbaria, https://ucjeps.berkeley.edu/

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