594 - Heredity and Evolution 



other questions will frequently arise and to names, mainly of Greek origin, are difficult, 

 some extent they will be answered. of course. However, they can be mastered 



with practice, especially by students who look 



up the derivations. 



THE SUBKINGDOM THALLOPHYTA 



OUTLINE OF THE PLANT KINGDOM 



The following outline gives the names of 

 the principal plant groups, with scarcely any 

 mention of their distinctive features. Such a The Cyanophyta (Blue-green Algae). Sev- 



bare map is designed to provide an orienta- eral genera of these algae are shown in Fig- 

 tion throughout the subsequent survey. The ure 31-1. Probably the blue-green algae are 



Kingdom Plantae (The Plants) 



Subkingdom I: The Thallopiiyta (Thallophytes) — Primitive plants. Mainly aquatic; do 

 not have any embryo stage in development. 

 Phylum 1 — The Cyanophyta (Cyanophytes) — Blue-green algae 

 Phvlum 2 — The Eiglenophyta (Euglenophytes) — Euglena-like algae 

 Phylum 3 — The Chlorophyta (Chlorophy'tes) — Green algae 

 Phylum 4 — The Chrysophyta (Chrysophytes) — Golden-brown algae (diatoms) 

 Phylum 5 — The Pyrrophyta (Pyrrophytes) — Flame algae 

 Phylum 6 — The Phaeophyta (Phaeophytes) — Brown algae 

 Phylum 7 — The Rhodophyta (Rhodophytes) — Red algae 

 Phylum 8 — The Schi'zomycophyta (Schizomycophytes) — Bacteria 

 Phylum 9 — The Myxomycophyta (Myxomycophytes) — Slime molds 

 Phylum 10 — The Eumycophyta (Eumycophytes) — True, or higher fungi 

 Subkingdom II: The Embryophyta. (Embryophytes) — Mainly terrestrial plants, more highly 

 developed, possessing an embryo stage, in the diploid generation. 

 Phylum 11 — The Bryophyta (Bryophytes) — Mosses and liverworts: most primitive of 



land plants. 

 Phylum 12 — The Tracheophyta (Tracheophytes) — Less primitive land plants. Possess 

 vascular tissues (xylem and phloem). 

 Subphylum 1 — The Psilopsida — Ancient group of land plants, noio almost extinct: vas- 

 cular tissues weakly developed; with no roots and virtually no leaves. 

 Subphylum 2 — The Lycopsida — Club mosses, spike mosses, and quilhvorts. Dominant 

 group in the Carboniferous period; now diminished to a relatively few 

 species; has roots, leaves, and simple vascular tissues; displays first be- 

 ginnings of heterospory. 

 Subphylum 3 — The Sphenopsida — Scouring rushes. Another almost extinct group; had 

 zenith in Carboniferous period; has roots, leaves, and vascular tissues, 

 but relatively weak adaptation to land conditions. 

 Subphylum 4 — The Pteropsida — Well-adapted land plants, dominant today; with com- 

 plex conducting tissues, extensive roots, and large conspicuous leaves. 

 Class 1 — The Filici'neae — Ferns 



Class 2 — The Gymnospermae (Gymnosperms) — Pines, spruces, cycads, and other 

 cone-bearing, seed-producing plants 

 Class 3 — The Angiospermae (Angiosperms) — Flower-bearing, seed-producing plants 

 Subclass 1 — The Monocotyledoneae (Monocotyledons) — The embryo has only 



one cotyledon (embryonic storage leaf). 

 Subclass 2 — The Dicotyledoneae (Dicotyledons) — Embryo with two cotyledons 



