California Mushrooms: The Comprehensive Identification Guide - Tapa dura

Introduction: What Are Fungi?
Fungi are organisms with a unique combination of features that distinguish them from plants, animals, and all other life forms. Kingdom Fungi comprises approximately 100,000 described species, although conservatively, it is estimated that over 1.5 million fungi occur on planet earth, and likely closer to 3 million. Fungi shared a common ancestor with animals 1–1.2 billion years ago, evolving from a population of aquatic, unicellular organisms with a single, posterior, whiplash flagellum, morphologically similar to a mammalian sperm cell or a chytrid zoospore. From this simple origin, a minimum of five distinct lineages arose, resulting in what we now recognize as the Chytridiomycota (chytrids and relatives), Zygomycota (bread molds), Glomeromycota (arbuscular mycorrhizae or endomycorrhizal fungi), Ascomycota (morels, cup fungi, truffles, yeasts, molds, mildews, and others), and Basidiomycota (rusts, smuts, gilled mushrooms, boletes, polypores, spine and coral fungi, puffballs, and allies). Fungi are mostly multicellular organisms (except for yeasts and some chytrids), with cell walls formed primarily from the complex polysaccharide chitin. The main body of a fungus is a filamentous chain of cells called hyphae, which form an extensive network of filaments known as a mycelium. Unlike plants that produce their own nutrition through photosynthesis, fungi, like animals, are heterotrophic, i.e., require an outside source of nutrition.

Fungi get their food by extracellular digestion of dead or living substrates, or their nutrition is provided by a photosynthetic symbiont (a plant, alga, or cyanobacterium). The mycelium is perennial and may live for decades or centuries, serving numerous ecological roles. Fungi reproduce and disperse by the formation of asexual (genetically identical) or sexual (genetically different) spores produced on the mycelium or in complex reproductive structures. The spore-producing structures are usually short-lived and form only under specific environmental conditions. The focus of this book is fungi that form sexual reproductive structures commonly called mushrooms.
 
About the Book
This book, a guide to the identification of mushrooms of California, of necessity focuses on the only part of the mushroom life cycle that is readily observable: the reproductive stage, i.e., the “mushroom,” defined here as the structure on which genetically variable sexual spores are formed for dispersal and reproduction. We include organisms from two major lineages of fungi—the Basidiomycota, whose sexual spores are formed externally on a cell called a basidium, and the Ascomycota, with sexual spores formed inside of a cell called an ascus. The mushroom-forming species included in this book occur within the boundaries of California, although most included species also occur outside of the state. Voucher specimens are deposited primarily in the Harry D. Thiers Herbarium at San Francisco State University (SFSU), with a few at the University of California, Berkeley (UC). The species descriptions are based on the following: personal observations of the authors from data documented over the past 30 years; unpublished data from other professional and amateur mycologists derived from California specimens; and published data on California species, verified by us from analyses of vouchered specimens. Data presented in the descriptions represent the variation observed in California populations, not the overall variation reported for the species throughout its entire geographic range. Most of the photographs in this book were taken in California; however, where representative photos were not available, a few photographs from Oregon and Washington were included. The attribution for each photograph is given in parentheses at the end of the photo legend; see Photo Credits for more information.

We estimate approximately 3000 species of mushrooms occur in California. Because of book limitations, we provide comprehensive descriptions of 650 species with reference and comparisons to an additional 475 California species. Species included in the book were chosen based on the following criteria: common species likely to be encountered year after year; representative species from a broad sampling of habitats ranging from deserts, grasslands, and bogs to coastal, central valley, foothill, and montane forests; species originally described from California or unusual species found only in California (endemics); and, finally, species for which quality photographs were available.

This book is designed to guide the reader as quickly and efficiently as possible to an accurate mushroom identification. For simplicity, the organization emphasizes mushroom body form and spore deposit color. Mushrooms have evolved a number of easily recognizable body forms adapted for maximum spore production and efficient spore dispersal. These include chanterelles and other gilled fungi, boletes, polypores, spine fungi, club and coral fungi, puffballs and allied gasteroid fungi, crust fungi, jelly fungi, morels, cup fungi, and hypogeous fungi. These body forms have evolved independently a number of different times, such that all species with a specific body form are not necessarily closely related. Our organizational strategy does not reflect phylogenetic relationships among the genera included. To do so would make the book confusing and unnecessarily complicated. For example, if we were to present the mushrooms in a phylogenetic context, we would have to include in one chapter all genera belonging to the order Russulales: the stipitate-gilled Russula and Lactarius, sessile-gilled Lentinellus, polypore Albatrellus, spine fungi Auriscalpium and Hericium, crust fungus Peniophora, stereoid fungus Stereum, and many others (see the table on page 000).

Each section begins with an overview of the mushroom group included, and a dichotomous key to help lead the user to an appropriate species description. Only species with full descriptions are included in the keys. Closely related species and look-alikes are compared in the comments that conclude each description.

Understanding the evolutionary history (phylogeny) of mushrooms informs our taxonomic concepts. The addition of molecular data to the suite of taxonomic characters upon which species circumscriptions are based has greatly advanced our understanding of species relationships and has consequently changed the taxonomy and the names used. For many years, mushrooms from California were identified using literature mostly based on species occurring in Europe or eastern North America. Recent molecular studies have indicated that many species in western North America are different from their counterparts to the east, even though morphologically they fit their published descriptions. As a result, different names must be used for western North American species. This research is ongoing, and fortunately a number of mycologists are actively studying California species in attempts to clarify their phylogenetic histories and taxonomic boundaries.

We have tried to use the most appropriate genus and species names for the mushrooms included in this field guide, based on available data. In most cases we accept the “current name” as listed in the websites Species Fungorum and MycoBank, unless we have contradicting data. Because the nomenclatural history of some species is long and confusing, we provide author citations for each species. These are the names that follow the specific epithet, indicating who the originating author of the species was or who transferred it into the currently accepted genus. We use the author citations and abbreviations as provided by the website Index Fungorum.