260 CONTRIBUTIONS FROM THE NATION.\L HERBARIUM. 



Calyx borne at the base of the ovary and inclosing the capsule; petals 



usually 5 SILENACEAE (p. 333). 



Corolla of united petals. 

 Fruit of 2 long pods; juice milky. 

 Pods glabrous; corolla bell-shaped; flowers in cymes. 



APOCYNACEAE (p. 395). 

 Pods woolly; corolla flat, with reflexed lobes; flowers in umbels. 



ASCLEPIADACEAE (p. 395). 

 Fruit not of 2 pods; juice not milky. 

 Corolla 2-lipped. 

 Fruit of 4 nutlets in the bottom of the calyx; corolla purple. 



Prunella (p. 402). 

 Fruit a capsule; corolla variously colored. 



SCROPKULAEIACEAE (p. 403). 

 Corolla not 2-lipped, the lobes all alike. 



Capsule 1-celled; corolla 15 to 40 mm. long, blue, purple, or lavender. 



GENTIANACEAE (p. 394). 

 Capsule 3-celled; corolla 3 to IS mm. long, white or purplish. 



POLEMONIACEAE (p. 396). 

 BB. Leaves alternate or else all borne at the base of the stem, the stems often naked 



(one or two pairs of the lowest leaves rarely opposite). 

 Leaves evidently parallel-veined; petals and sepals, when present, 3 each (in a few 

 plants the leaves are net-veined, but these are easily distinguished by the 3 

 petals). 



Flowers sessile in dense globose heads SPARGANIACEAE (p. 277). 



Flowers not sessile in globose heads. 

 Flowers sessile in dense cylindric spikes, the lower part of the spike brown and 

 velvety; plants about a meter high, with spongy linear leaves. 



TYPHACEAE (p. 277). 

 Flowers not as above; plants various in habit. 



Flowers sessUe in a spike, this surrounded bj' a yellow hood-shaped corolla-like 

 spathe, the whole appealing like a single flower; leaves all basal, 7 to 25 cm. 



wide AKACEAE (p. 304). 



Flowers never in a sessile spike surrounded by a spathe; leaves various. 

 Fruit a head of numerous small achenes; petals white; leaves arrow-shaped or 



ovate ALISMACEAE (p. 279). 



Fruit not a head of achenes; petals variously colored; leaves various but 

 never arrow-shaped . 

 Petals unlike, one of them very different from the other two. 



ORCKIBACEAE (p. 314). 

 Petals all alike. 

 Fruit of 3 to 6 distinct pods; flowers in loose racemes, the petals white. 



SCHEFCHZERIACEAE (p. 279). 

 Fruit never of distinct pods; flowers various. 

 Petals (blue) and sepals borne at the top of the ovary; leaves with 

 their edges turned to the stem; stamens 3; fruit dry. 



miDACEAE (p. 314). 

 Petals and sepals borne at the base of the ovary; leaves usually with 

 one face turned to the stem; stamens 6; fruit dry or juicy. 



LILIACEAE (p. 308). 



