200 PBAOTIOAL BOTANY. 



533. Stamens alternate with the corolla-lobes. Style 1, 

 beset with collecting hairs above ; stigmas 3. Ovary 3-celled. 

 Pod opening on the sides by holes or valves. Corolla wheel- 

 shaped. 524 



Stamens opposite the corolla-lobes. Style and 

 stigma 1. Ovary 1-celled, with a free central placenta. 

 Corolla somewhat bell-shaped, usually with 5 sterile lilaments 

 in the sinuses. (365) Samolus Valeraudi, L. 



534. Pod prismatic, elongated. Flowers axillary and 

 terminal, sessile, erect, 2-3 together ; the lower ones fruiting, 

 without expanding. Filaments hairy, membranaceous. 

 Leaves small, roundish-ovate, toothed, clasping by the 

 cordate base. Specularia perfoliata, A. D.C. 



Pod shoi-t, not prismatic. Flowers panicled, or 

 crowded in a long, leafy spike. Filaments naked, broad and 

 membranaceous at the base. Campanula. 



535. (509.) Stamens as many as the corolla-lobes. ...526 

 Stamens fewer than the corolla-lobes, 2 longer than 



the other. The 5-lobed corolla purple and whitish, hairy 

 inside. Berry 3-celled, indehiscent, 1-seeded (2 cells abortive). 

 A trailing, evergreen herb. Stem creeping. Leaves small, 

 roundish, opposite, petioled, obtusely lobed or toothed. 

 Peduncles 2-flowered, about 3 inches high, thread-form, 

 slightly pubescent (the only erect part of the plant). 



Iiinnsea borealis, Gron. 



536. Numerous flowers in a naked or involucrate head. 

 Fruit dry 527 



Flowers not in heads 5?8 



537. Heads not involucrate, globular, about 1 inch in 

 diameter, Or larger. Style much exserted. Shrubs, with 

 stipules. Cephalauthus occidentalis, L. 



Heads involucrate, oblong, about as large as a hen's 

 egg. Stipules none. Involucre many-leaved, long'ef than 

 the chaffy, leafy-tipped and pointed bracts among the flow- 

 ers. Flowers bluish, the middle zone of the head expanding 

 first, each with a 4-sided involucel, closely investing the calyx 

 in fruit. Fruit 1-seeded, crowned with the calyx. Corolla 

 4-cleft. Style slender. Stout and coarse, prickly perennial 

 herbs. Leaves lance-oblong, opposite, connate. 



Dipsacus sylvestris, Mill. 



