viii 



KEY TO GROUPS 



la. Trees, shrubs, or woody climbers, with stems which last from 

 year to year Group 1, WiHlDY^PJLLXJS, p. ix. 



Ib. Herbaceous plants, with stems which live above ground only a 

 "single season 2. 



2a. Plants with unusual habits or structures, including leafless, 



colorless, submerged, floating, parasitic, or hollow-leaved plants 



% Group l\ U> i USUAL I'LA^TS, p. xxiii. 



2b. Ordinary terrestrial or swamp plants, without unusual 



3. 



3a. Leaves parallel-veined (or net-veined in a fe'w species) ; parts of 

 the flower usually in threes or sixes, never in fives; wood- 

 fibers scattered through the stem; seed with one cotyledon. 

 All plants with definitely parallel-veined leaves may be identi- 

 fied through this division, unless the parts of the flower are dis- 

 tinctly in fives. Group 3, MONOCOTYLJEDONES, p. xxvii. 



3b. Leaves net-veined (or parallel-veined in a few species) ; parts 

 of the flower usually in fours or fives; wood-fibers arranged 

 in a circle in the stem; seeds with two cotyledons. All plants 

 with definitely net-veined leaves may be identified through this 

 division. Group 4, DICOTYLEDONES, p. xxx. 



Note: In order to avoid possible chances of error, many plants 

 have been treated under both of the above groups. The following 

 hints may also be useful in distinguishing Groups 3 and 4: 



All herbaceous plants with deeply lobed, dissected or compound 

 leaves may be sought under the Dicotyledones. 



All herbaceous plants with five stamens in each flower, or with 

 seven or more stamens and one ovary in each flower, may be sought 

 under Dicotyledones. 



