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APPENDIX A 



\ 



Gymno- 

 spermae 



SPERMA- 

 TOPHYTA 



Angio- 

 sperinae 



Class 2. Gymnospermae. The Lower Seed) 



Plants. 

 Subclass 1. Cycadophytae. The Cycad Line. 



Order 1. *Cycadofilicales. The Seed Ferns. 



Order 2. Cycadales. The Cycads. 

 Subclass 2. Coniferophytae. The Conifer Line. 



Order 1. *Cordaitales. The Large-lea ved( 

 Evergreen Trees. 



Order 2. Ginkgoales. The Ginkgoes (Ginkgo, 

 1 species living). 



Order 3. Coniferales. The Conifers. 

 Class 3. Angiospermae. The Flowering Plants. 

 Subclass 1. Monocotyledonae. The Monocots. 



Order 1. Graminales. The Grasses. 



Order 2. Liliales. The Lilies. 



(And many others.) 

 Subclass 2. Dicotyledonae. The Dicots. 



Order 1. Ranales. The Buttercups. 



Order 2. Rosales. The Roses. 



Order 3. Geraniales. The Geraniums. 



(And many others.) 



The most important characteristics of the four great plant divisions 

 have already been described and discussed in the section on the major 

 patterns of plant life (Chap. XIII). Here these features will be recapitu- 

 lated briefly, and our attention will be given more particularly to the 

 principal subphyla, classes, and orders of plants. 



Phylum I. THALLOPHYTA (tha lof it a; Greek, thallos, "young 

 shoot or frond," phyton, "plant"). 



The thallophytes (thai' o fits) are the simplest plants — unicellular, 

 or with a body composed of simple, relatively unspecialized cells that 

 make up a thallus. Including the unicellular Protophyta (pro tof it a), 

 the phylum comprises some 84,000 species. These fall into two major 

 groups — the algae, which possess chlorophyll and carry on photosyn- 

 thesis, and the fungi, which lack chlorophyll and must obtain their food 

 from other organisms (or rarely by means of chemosynthesis). 



Subphylum I. Algae (al' je). Seaweeds, pond scums, and a host of 

 microscopic water plants make up the bulk of the 14,000 species of this 

 group. A few are terrestrial; most of these live in moist situations, but 

 some are symbiotic with fungi, forming lichens that often occur on bare 

 rock and in other very dry places. Although most algae are small, some 

 of the giant seaweeds called kelps attain a length of more than 100 feet. 

 Five major groups are distinguished, and some authorities recognize 

 additional ones. 



