Presidio

Date: 12/14/2019

Location: Batteries to Bluffs Trail in the Presidio, San Francisco CA

Coordinates – 37.796835, -122.479460

Site Description: Coastal cliff habitat with many low shrubs and herbs that overlook the ocean. Next to the trail was a rocky, serpentine outcrop where not a lot was growing. Sub-habitats included streams, cliffs, and dense clusters of shrubs. Dominant species included the non-native ice plant (species unidentified), coyote brush (Baccharis pilularis), and other low shrubs like the lupines and lizard’s tail (Saururus cernuus). Tree cover was rare, but occurred in patches rather than 1-2 trees at a time. The plants in this area must have good adaptions to preventing desiccation, as it tends to be a very windy area around this time of the year.

The weather for our trip was mildly cloudy in the beginning with sparse, light and infrequent rain showers. We departed USF around 1:00pm and arrived in the Presidio at about 1:30pm. Parking the vans on the side of the road, we began at the Batteries to Bluffs Trail in the Presidio. This area was historically a military area, where they once planted many Monterey cypress (Cupressus macrocarpa) trees to bring shade/cover to the area. Most of the trees have since been removed and the Batteries to Bluffs trail, with the help of non profits like Presidio Trust, has somewhat returned to the low-shrub, coastal habitat that it was once believed to be.

One of the first plants that we saw on the trail was the coffee berry (Frangula californica). At first glance, this shrub looked a lot like what would traditionally be known as holly with rich green leaves and small red berries. Similar to holly, coffee berry has dentition on the margins of its leaves, though they appear to be way less extreme. Coffee berry appears in the family Rhamnaceae, within this family flowers often have structures in parts of 5. On the coffee berry, these flowers appear to be a light yellow-ish color. These plants can either grow in the understory of other plants or they can grow out in the open. When grown in the understory, coffee berry tends to have larger leaves to compensate for its placement. If it grows out in the open, it must face the harsh elements that come along with surviving on the coast. As with any coastal plant, this plant faces the threat of desiccation from strong winds. Additionally, sometimes their leaves might appear to be reddish in color-this is because they’re younger leaves that will eventually be predated on by hungry animals. Filling younger leaves with chloroplast comes at a great energetic cost that sometimes does not seem to be beneficial if the leaf is going to get eaten anyway. 

(Left: Yellow lupin; Right: Beach blue lupin)

Continuing along the trail, we saw two species of lupin: Yellow lupin (Lupinus arboreus) and beach blue lupin (Lupinus chamissonis). Although these shrubs looked quite similar from afar, they proved to be different upon closer inspection. Beach blue lupin appeared to be a darker blue-ish green color while the yellow lupin was a more ‘true-green’ color. Both plants had flower-shaped leaves that were palmately compound. These plants fall under the family: Fabaceae. The yellow lupin will give rise to yellow flowers while the beach blue lupin will give rise to purple flowers. Across the Golden Gate Bridge, however, Lupinus arboreus may appear to be purple as well.

One of the more common families that we found throughout the Batteries and Bluffs trail was the Rosaecae family. Flowers from this family sometimes have thorns, but more commonly they have white flowers. Here are some of the species that we observed along the way:

(Pictured below, middle: California Blackberry)

  1. Oso Berry (Oemleria cerasiformis)
  2. California Blackberry (Rubus ursinus)
  3. Coast Strawberry (Fragaria chiloensis)

I haven’t thought much about it before, but it seems that a number of plants in the Rosaceae family are edible. I am excited to learn during the progression of the semester the different families some of my favorite fruits and vegetables belong to.

 

 

 

One tree that we ran into during our hike, which I have mentioned previously, was the Monterey cypress (Cupressus macrocarpa). This tree, that looks very similar to a pine tree, used to be prevalent in the Presidio, however it is not native and halts many other plants from growing due to the large shadow that it casts. It has since been removed in many areas of the Presidio by restoration efforts. This gymnosperm has pressed needle-like leaves against a stem and belongs to the family Cupressaceae. The tree pictures above is a female, as it contains many round cones which Dr. Paul described as looking like a ‘mini-globe’.

Another type of tree that we saw was the arroyo willow (Salix lasiolepis), a diecious and deciduous tree-shrub. This tree is in the family Salicaceae and its bark is responsible for the production of salicylic acid. Its leaves normally appear in alternate positions and are simple, lanceolate leaves with a whitish underside. The leaves have fallen off for now, but will start to come back again after winter is over. The specimen pictured to the left is a male with blooming catkins. These reproductive structures have many anthers on them for spreading pollen, which is most likely distributed by wind to the female trees.

 

Summary – This trip was a wonderful way to familiarize ourselves with a lot of the shrub-life found in California. I hadn’t realized it until the end, but in many of my other field classes we had seen a lot of the plants that we saw in the Presidio. Coyote bush specifically was one of the ones that dominated the landscapes of the California planes and mountains that we visited. This field trip was a great way to expose ourselves to some new plants and recall some that we found on our Baltimore Canyon trip. I will definitely be returning to this site to study for the field exam.

(Additional Species)

–To be posted later–

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