Introduction to Native and Introduced Plants of Southern California

We have long been interested in the plants along the trails we hike. Tom began a Plants Blooming page for the San Gabriel Mountains in 1997 with a grand total of seven species; Jane expanded the page to 137 species in 2000 and began to share her expertise with Tom. However, our just-a-bit-more-than-casual interest became a pleasant obsession with us beginning in early 2001, almost by accident.

On February 14, 2001, the day the Vernal Pool at the Santa Rosa Plateau filled that year, Tom began hiking there every 2-3 days to observe the evolution of the Vernal Pool. As an unexpected byproduct of tracking the Vernal Pool, Tom soon began tracking all the plants blooming on the trails there. Tom soon enlisted Jane in a project to identify every new species of plant as it bloomed, as well as keeping track of the bloom times for each species.

At nearly the same time, Jane had signed up to lead a California Native Plant Society (CNPS) walk at Mt. Hillyer on May 19, 2001. On an exploratory trip there with Bob Muns, Bob made the fateful suggestion to Jane: Why not make up a list for this trail for your hike?

We had long known the power of having a plant list that was provided by someone else (see Introduction To Our Trail Guides); this was the first time someone had suggested that we make a plant list ourselves.

Both the Santa Rosa Plateau and Mt. Hillyer projects were so pleasurable that we soon picked a high-elevation trail in the San Gabriel Mountains, the Big Horn Mine Trail, to study that area in the same way. In order to help learn the species on that trail, we kept our list not in the traditional family order, but instead in order along the trail. That way we could go back to the precise location of a species, and study it on each trip without having to figure out all over again which species it was.

With that, we were hooked. Essentially ever since February 2001, we have spent nearly full-time learning the species along trails and making plant guides for those trails. This website is the outgrowth of that work, and was first placed online in September 2002.

There are four major divisions of this website, discussed separately in each section below:

Our Master List of Southern California Taxa

Our Master List is a database that consists of:

Fundamentally, our Master List gives a record of where we and others have found each and every taxa found in Southern California. Occasionally we call this our Master Database as well; they are one and the same.

We began the Master List by downloading the Calflora Database on 22 January 2002. This database contains every taxon present in California, as defined by the Jepson Manual, with a large amount of useful information for each taxon. It includes the common names, full Latin names, older Latin names used in A Flora of Southern California by Munz, elevation ranges, habitats, and counties in which the taxa are found.

Note that the Calflora Database also includes the taxa sometimes given at the end of the taxon descriptions in the Jepson Manual. It is often erroneously thought that these taxa are "not present" in the Jepson Manual, which is not the case. The Jepson Manual states that these taxa are unclearly differentiated forms, and reserves judgment about (but calls into question) whether a form should be considered taxonomically distinct. We use those taxa in our Master List when appropriate, either from our records when we think those taxonomic distinctions are valuable, or from the records of others who use those taxa.

We selected only those taxa found in Los Angeles, San Bernardino, Riverside, Orange and San Diego Counties for our initial Master List, since we have done most of our botanizing in those counties. Therefore, strictly-speaking, we are dealing with a subset of Southern California, but it is too much of a mouthful to call our site Native and Introduced Plants of Southern California except for Ventura, Imperial, and a portion of Santa Barbara Counties. Also, we may in the future include at least a portion of those counties.

For comparison, see the floristic definition of southern California.

Having this list to start with has made our task tremendously easier, both in producing our Master List and in helping with our plant identifications. For example, to digitize a Flora or our observations of species for a Trail Guide, we simply have to check off a column in our Master List. We especially appreciate the fact that it ensures that our spellings are correct!

We have slowly added our data to the Master List. Of course, our Master List is presently far from complete, since we just began the compilation of this List in early 2002. See Number of taxa vs time for a record of how many taxa are contained in our Master List at present from our Trail Guides and from the floras we have digitized.

We add taxa to our Master List as we come across them, either in our Trail Guides or in adding flora from others. These additional taxa fall into several categories:

Our Trail Guides are the core of our Master List. See Introduction and Explanation of Trail Guides for more information about the Guides. We keep track separately of elevations where we find taxa, since the Jepson Manual elevation ranges are sometimes too wide, reflecting occurrences outside of Southern California, and sometimes too small, reflecting a lack of knowledge about actual occurrences in Southern California.

Our Regional Floras are derived from our Master List, by producing a mini-Master List just for a particular area of Southern California. If one is interested only in a given area, it is much more useful to have a mini-Master List (which is what a Regional Flora is) containing perhaps 500 species for that area than to use a Master List with over 4,000 species.

The major use of our Master List for most people is probably the ability to know specifically where to see a live, physical specimen of a given taxon. In addition to those people who simply want to see a given taxon, it is often very helpful for plant identification of one taxon to see all the other similar taxa. We've found that among the most powerful methods of plant identification is simply to see all the closely-related species that might be confused with each other. Often, they exhibit dramatic differences that are not captured or conveyed well in a key or in the terse written description found in most floral guides.

With our Master List, it is easy to find all occurrences of a given taxa on all the trails we have surveyed, so that one can go to the closest trail and actually find that species. Here's an example of an actual request to find occurrences of Clematis ligustifolia:

Found in two regional flora: South Coast (SCo) and San Gabriel Mountains (SnGb).

In South Coast, found on one trail: Crystal Cove State Park, Green Route, plant #52 at mile 1.54.

In San Gabriel Mountains, found on 3 trails:
Sulphur Springs, plant #58 at mile 0.38.
Manzanita Trail from the top, plant #65 at mile 1.50.
Big Horn Mine Trail, plant #50, at mile 0.22.

We haven't yet had time to put our current version of our Master List online. Our intent is to use the Regional Floras to present the information in a more manageable way. Thus the webpage giving the Master List will tell you which Regional Floras contain that species; the Regional Floras will list the individual regions or trails where that species can be found.

Until we have the Master List online, the easiest way by far to find all occurrences of a taxon is to search for it, using a search restricted to our site.

As part of the compilation of all the Floras we could find, with the help of Michael Charters we are digitizing all of the many Floras of Bob Muns, and making those available separately.

The compilation of various floras and vouchers is often much more interesting and informative than having a single plant list for a region. See, for example, the Torrey Pines Flora and look at the differences between the two floras there so far. (It is even more interesting when the vouchers are added, but we haven't put them in our database for Torrey Pines yet.)

The order in which we compile our Regional Floras is determined by the trails we hike. When we hike a new trail, we try to compile all the information about that area at the same time. Due to our spending most of our time on plant identification, sometimes it takes a while to get that information online.

Once we get a significant number of external plant lists in our database, we'll publish a list of the ones we have, so that we can enlist our readers help in acquiring other lists.

Our voucher records come from the Calflora Occurrences Database. This is a wonderful, easy-to-use resource that contains a significant number of vouchers for most Southern California taxa. Unfortunately, the premier collections of vouchers for Southern California plants are not available online.

The Herbarium at the Rancho Santa Ana Botanic Garden (RSABG) has one million vouchers, with most of them for Southern California, whereas Calflora has 0.9 million vouchers, with most of them for Northern California. The Herbarium at the San Diego Natural History Museum (SDNHM) has 0.15 million vouchers, with most of them for San Diego County. RSABG is still in the process of digitizing its collection, having digitized something like 20% of the collection as of mid-2002. Whenever their database is available, that will significantly increase the number of vouchers in our Regional Flora. Unfortunately, we have heard that the SDNHM herbarium database is considered proprietary, so it is unlikely we will be able to incorporate their vouchers in our Regional Flora, even after it is digitized.

Comments on the Jepson Manual and A Flora of Southern California by Munz

This page is the outgrowth of the numerous identification attempts we have done in the course of our studies. It records some of the problems we have had with identification using the floras, and what we actually have observed for a number of species. See the page for more information.

Analysis Pages

Our analysis pages consist of two types of analysis:

General Information

As part of our Field Guide to the San Gabriel Mountains: Natural History: Plants, we began some years ago to compile information on California Plant Pictures and Databases, California Oaks, and pages reporting Plants Blooming Now in Southern California. This section primarily contains links to other pages giving that information, with the links in California Plant Pictures and Databases sorted in order of the number of California species at each link. Consult those pages to see the kind of information contained there, for example, California Plant Pictures and Databases.

Go to Native and Introduced Plants of Southern California

Copyright © 2002-2007 by Tom Chester and Jane Strong.
Permission is freely granted to reproduce any or all of this page as long as credit is given to us at this source:
Comments and feedback: Tom Chester | Jane Strong
Last Update: 14 August 2007.