GEOG/ES&P 330

California Ecosystems

Flattened Flora

Keying out CSS Plants from Herbarium Specimens
(virtually, in lieu of my actual herbarium, during COVID-19

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Flattened Flora: Introduction to Herbarium Specimens and Keying

An herbarium is a collection of pressed and dried botanical specimens, which are eventually mounted on archival paper (which might last centuries!), together with information on the then-current Linnæan binomial name, and often the local common name. Normally, the date the sample was collected is provided, as well as a description of where it was collected, so someone else might go back to monitor the area. The description might be something like "Chatsworth, California; Stoney Point Regional Park along the path along its southern border, 100 m east of Topanga Canyon Blvd., 3 m north of the ephemeral streambank." More recently, people are putting latitude, longitude, and elevation from GPS, along with datum (e.g., WGS84). Some collectors will give extensive descriptions of the surrounding vegetation, too. The collector should have included his or her own name.

Herbaria have their roots (metaphorically speaking) in the collection activities of individual hobbyist collectors centuries ago. With the advent of colonialism, imperialism, and exploration, plant collecting became a global activity and attempts were made to systematize procedures for pressing and drying specimens and identifying them. The stunning variety of plant life across the planet, as well as systematic differences and similarities among individual specimens led to attempts to classify life, as represented by Carl Linnæus' efforts to produce the famous binomial nomenclature in the eighteenth century. They provided the glimmer of what would become recognized as evolution as people wrestled with systematizing the diversity seen in herbaria, living plant collections, animal skins and skeletons, and living animal collections. Charles Darwin himself made herbarium pressings and his family was active in botanizing and plant pressing. His work on the five year trip on the HMS Beagle entailed collecting and then sending shipments of botanical, zoölogical, and geological specimens to Cambridge University. While engaged in this work, he began to develop his ideas on the mechanisms of evolution nd of species differentiation. So, herbaria were critical sources of data in the development of evolution and of life classification systems.

Herbaria have become important sources of data far beyond the taxonomic/systematic uses they served for most of their existence. There are so many herbaria (hundreds) with so many plant specimens (>350,000,000!), many of these repeat collections of the same species, that many large and small herbaria are getting together to develop standards for imaging these for online access. If you like (optional), you can access an overview of the US Virtual Herbarium effort: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3406466/ This broadening access allows possibilities for much different applications to emerge.

For example, climate change has driven changes in the length of growing seasons and in the timing of seasonal greening and reproductive activities (phenology), and it is now possible to estimate the responses of particular species to these changes by collecting information on hundreds, even thousands of samples of the same species and observing their phenological stages and noting the year and time of year they were collected. With new DNA and protein analysis techniques, herbaria are potentially able to monitor DNA changes and evolution over time (some herbaria and samples are quite old, going back to the sixteenth century). Given the age of some herbaria, it is possible to use their collections to estimate the changing distribution of particular species through time. Herbaria have become increasingly widely accessible archives of information to pursue topics like these!

I maintain a small, informal herbarium of my own plant collection activities over the years as I go out to scope student field trips. It contains representative small samples of common species in various of my field sites (Charmlee Park in Malibu, Stoney Point Park and the Sepulveda Dam Basin in the San Fernando Valley, Portuguese Bend and Forrestal Preserve on the Palos Verdes Peninsula, mainly. They also include "mystery plants" that I needed to take back to the lab to try to identify. This rather funky herbarium is the source of collections of dried plants I assemble into folders with other helpful information for student teams to use to go through the keying process a few times. It is housed in my lab, which I can't access due to COVID-19 and, so, neither can you.

So, what I've done is searched for digitized herbarium samples of the species I most commonly use for this purpose, and we'll use these images in lieu of an actual flattened plant mummy! I've put together fifteen packages, and each student team will key out three assigned to them. The way this works is that each person will go through the process with all three of the "folders" and then s/he will confer with the other person working on the same group. Did you come up with the same identifications? If so, whew! If not, you need to confer and figure out how each of you diverged on a critter to figure out who got lost in the key, straighten it out, and then certify a common list of identifications. You will also get to cross-check with one or two other teams.

This lab has three purposes:

  • to give you experience in keying out species from dried herbarium samples
  • to familiarize you with several local California sage scrub species, so that you can recognize them on sight in the field
  • to give you an opportunity to engage in some team-work, which had been a major part of this class before COVID-19
  • optionally (not graded), you could just keep on going and see if you can identify more species, just to build up practice so you're more comfortable with the process


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Your Data

Your data are presented below. The main link in each case is a anonymized herbarium sample that's been made available by several different herbaria. Focus your initial energy on examining that image of "flattened flora." There is a checklist that will help you focus on observing the most helpful traits. Use it and fill it out as far as you can from what you can see. There is no need to find and fill out every single item on the checklist since not all are relevant (and you will not be turning this sheet in: It is purely to help you aim your attention and pick up a habit of systematic observation). The checklist is here:

After each herbarium specimen, there is a set of photographs of the living plants, with up close images of their inflorescences and their leaves and stems and an image of the whole plant as it appears in the landscape. These help you see the natural colors of your herbarium specimens, which, besides being flattened, have their original colors altered by drying. These images can help you identify your critters if you can't make them out from the herbarium specimen and help you validate identifications you were able to make.

All specimens are from shrub species, so just use the shrubs link in the Palos Verdes key (see course home page). Taller shrub species are toward the top of that page, so if the plant is often >~2 m tall, start there. Smaller shrub and subshrub species are toward the bottom of the page, and you can fast-forward there by clicking on the "smaller shrub" link at the top. If you're working with what you think is a smaller plant and you're not able to pin its identity down, you can click on the "larger shrub" link down there to go back up to the top and try keying it as a larger shrub. This part of the key is a little confusing (large vs. small shrubs). Each student team's names are listed besides the team's three species.

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Procedure

Each team is responsible for three identifications. Team work is going to build up from the individual to the team working on the same three species. Then, two or three teams will compare their identifications (there are fifteen plants and only fourteen teams). The way this works is each person works through the identification of their three critters by, first, filling out as much of the checklist sheet for each species as they can and, then, by going through the Palos Verdes key with those characteristics (and with the specimen and life photographs of each) to identify it (read the description for your guesses to see if it rings true and click on some of the Calphotos links to verify it: You may even find some of the photos I used!). To find which species you were assigned, it might be easiest to do a Control-F (find) within this web page for your last name, which should occur three times.

Then, e-mail your team-mate via BeachBoard. You probably need your first message just to give him or her your "real" e-mail as BeachBoard is pretty awful for replying and conversing. Then, ask one another what you got for your three identifications. If they are the same, YAY! If they are not, then you need to give one another your series of decisions on the errant plant and figure out where you diverged. Discuss your decision trees until you converge on an agreed identification for all three.

Now, figure out which other teams did each of your three species (two or three teams worked on each of the fifteen species, but their lists don't overlap, so this means contacting two to four other students to see what they got for a given plant. If there are divergences, again, talk them through and modify your decision or stick to your guns.

Then, each team of two should have one of you upload your final identifications on the BeachBoard Dropbox for Lab 5. Please be sure to indicate which team the file represents (e.g., Team 4 or Team 15). Use this answer form to fill out and upload:



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Your Flattened Flora

Sample 1 (plant is typically about 2-5 m tall)
Herbarium specimen

Sample 2 (plant is typically about 1-8 m tall)

Herbarium specimen

Sample 3 (plant is typically about 1.5-5 m tall)

Herbarium specimen

Sample 4 (plant is typically about 2-5 m tall)

Herbarium specimen

Sample 5 (plant is typically about 0.5-1.5 m tall)

Herbarium specimen

Sample 6 (plant is typically about 2-4 m tall)

Herbarium specimen

Sample 7 (plant is typically about 1-3 m tall)

Herbarium specimen

Sample 8 (plant is typically about 0.25-2 m tall)

Herbarium specimen

Sample 9 (plant is typically about 1-2 tall)

Herbarium specimen

Sample 10 (plant is typically about 1-1.5 m tall)

Herbarium specimen

Sample 11 (plant is typically about 1-2 m tall)

Herbarium specimen

Sample 12 (plant is typically about 0.75-3 m tall)

Herbarium specimen

Sample 13 (plant is typically about 0.5-1.5 m tall)

Herbarium specimen

Sample 14 (plant is typically about 0.5-1.5 m tall)

Herbarium specimen

Sample 15 (plant is typically about 0.5-2 m tall)

Herbarium specimen


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The original images came from the online herbaria at the following universities:
  • Cal Poly San Luis Obispo
  • San Diego State University
  • Tulane University
  • Norton Brown
  • University of Texas
  • Brigham Young University
  • University of Georgia
These were then anonymized to allow the keying process as a stand-in for my own instructional herbarium specimens during the COVID-19 crisis.

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This document is maintained by Dr. Rodrigue
First put on the web: 09/17/20
Last Updated: 09/24/20

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