Artificial Analytical Key to the Higher Taxa 

 of Aquatic and Wetland Vascular Plants 



Key to the Major Groups 



1. Rushlike, fernlike, mosslike or quill-leaved plants without true seeds or flowers, 

 reproducing chiefly by spores I. Pteridophyta, p. 17 



1. Habit various; plants producing seeds (2) 



2(1). Plants producing seeds but not true flowers, i.e., either having "cones" 

 (with seeds borne more or less exposed on the upper surfaces of 

 the scales of the cones) or fleshy structures with the basic struc- 

 tures of cones (as juniper "berries"), or cones with only a few thin 

 scales (as in Ephedraceae) II. Gymnospennae, p. 19 



2. Plants producing true flowers, i.e., the seeds borne enclosed in specialized 



structures (ovaries) (Angiospermae) (3) 



3(2). Plants with several if not all of the following characters: vascular bundles 

 scattered in the usually solid internodes (these bundles can be seen 

 as scattered dots in the stem-transection) ; cotyledon (seed leaf) 

 solitary; when flower parts in whorls then some in whorls of 3, at 

 least not in whorls of 5 parts; leaves parallel-veined; root system 

 fibrous (i.e., most roots adventitious); plants nearly always herba- 

 ceous III. Monocotyledoneae, p. 19 



3. Plants with several if not all of the following characters: vascular bundles of 



young stems forming an interrupted cylinder (seen as a ring of dots 

 in stem-transection); cotyledons usuaUy 2, rarely more or one; 

 flower parts (when in whorls) often in 4's or 5's, less often in 3's, 

 2's, 6's, etc.; leaves usually reticulate-veined; roots either fibrous or 

 not; plants herbaceous or woody, the wood forming concentric 

 layers when present; young stems nearly always hollow or with a 

 pithy zone in the center.; IV. Dicotyledoneae, p. 23 



I. Pteridophyta (p. 37 of text) 



1. Foliage leaves scalelike or long-subulate, sometimes united into toothed 

 sheaths (2) 



1. Foliage leaves or entire frond with broad or narrow, entire, toothed, pinnate, 



pinnatifid or variously dissected blades (6) 



2(1). Stems hollow, fluted, jointed; sporangia borne under peltate scales in a 

 cone 5. Equisetaceae, p. 45 



2. Stems solid, not fluted or jointed; sporangia borne in the axils of scalelike or 



small leaflike or long-subulate bracts (3) 



3(2). Leaves rushlike, long-subulate, more than 3 cm. long, borne in a tuft on a 

 short cormlike stem 4. Isoetaceae, p. 41 



3. Leaves scalelike, flat, sometimes concave or cymbiform, less than 3 cm. long, 



borne on erect or creeping elongate stems and branches (4) 



17 



