SYSTEMATIC TREATMENT 



Key to the Sections 



Group I. Seed Plants. Plants normally reproducing by seeds containing an 

 embryo. Gymnosperms and Angiosperms. 



A. Herbaceous Plants 



1. Plants grasses, sedges, or rushes; perianth green or brownish or absent 



Section 1, p. 9 



1. Plants not grasses, sedges, or rushes. 



2. Terrestrial plants, not floating on or submerged in water; sometimes 

 growing at the edge of water but then usually erect. 

 3. Leaves compound, composed of few or many leaflets, or divided to the 



midrib or base Section 2, p. 9 



3. Leaves simple, sometimes lobed, but the lobes usually not extending to 

 the midrib or base (leaves rarely absent or reduced to spines or 

 scales). 

 4. Stems not climbing or twining; tendrils absent; plants never cacti or 

 cactus-like. 

 5. Plants green, normally possessing chlorophyll, not parasitic or 

 saprophytic or noticeably so. 

 6. Plants without a leafy stem, or the stem underground, the 

 flower-stalks leafless, or with a single leaf or a pair or whorl 



of leaves subtending the inflorescence Section 3, p. 12 



6. Plants with leafy stems, the leaves sometimes reduced to scales; 

 stem sometimes with only a single leaf, but this borne far 

 below the inflorescence. 

 7. Leaves evidently parallel- veined ; mostly Monocotyledons (ex- 

 cept Eryngium and Tragopogon) with the floral parts, or 

 some of them in threes, not in fives; stem in cross-section 

 showing the vascular bundles irregularly distributed 

 throughout the pith or around a central cavity; cotyledon 



1 Section 4, p. 15 



7. Leaves not evidently parallel-veined, almost always net- 

 veined (or sometimes apparently only 1 -veined) ; mostly 

 Dicotyledons (except Trillium and Smilax) with the floral 

 parts often in fives or fours, only exceptionally in threes; 

 stem in cross-section showing a central pith (or, in hollow 

 stems, a cavity) surrounded by a circle of vascular bundles; 

 cotyledons 2. 

 8. Leaves, or at least some of them, opposite or whorled. 



9. Leaves entire Section 5, p. 15 



9. Leaves more or less toothed or lobed Section 6, p. 19 



8. Leaves alternate. 



10. Leaves entire Section 7, p. 20 



10. Leaves toothed (or sinuate) or lobed, sometimes 



cordate at base Section 8, p. 23 



5. Plants parasitic or saprophytic, without chlorophyll; leaves re- 

 duced to scales; fruit a capsule Section 9, p. 25 



8 



