THE APETALOTJS ORDERS. 



459 



Group 7. Flowers monoecious or dioecious ; the sterile, and frequently the 

 fertile also, in aments, or in heads or spikes. Ovary often two- to several- 

 celled, but the fruit always one-celled. Trees, shrubs, or (only in Urti- 

 cacea?) herbs. 



* Fruit drupaceous. Calyx adherent. JCGLANDACE;E, p. 471. 



* * Fruit a nut, involucrate. Calyx adherent. CUPULIFERJE, p. 471. 



* * * Fruit one-seeded, indehiscent. Fertile and sterile flowers both in 



aments, and entirely destitute of calyx. 



Ovary one-celled ; ovule solitary, erect. MYRICACEJE, p. 472. 



Ovary two-celled, two-ovuled: ovule pendulous. BETULACEJE, p. 472. 



* * * * Fruit dehiscent, many-seeded. Seeds with a coma. Fertile and ster- 



ile flowers both in aments, and destitute of calyx. SALICACE.SE, p. 473. 



* * * * * Fruit a nut or a two-celled and few-seeded capsule. Fertile and 



sterile flowers both in aments or heads, and destitute of calyx. 

 Capsule two-beaked, many-seeded. BALSAMIFLU.S:, p. 474. 



Nut club-shaped, one-seeded, bristly-downy. PLATANACE.E, p. 474. 



****** Fruit an achenium, often inclosed in a baccate calyx. Flowers 

 variously disposed, sometimes collected in fleshy heads. Juice milky, 

 when trees or shrubs. . URTICACEJE, p. 474. 



858. Ord, Aristolochiaceffi (the Birthwort Family). Herbaceous, 



967 



FIG. 966. Asarum Canadense. 967. Calyx displayed, and a vertical section through the 

 rest of the flower. 968. Cross-section of the ovary ; the upper portion (from which the limb of 

 the calyx is cut away) showing the stamens, the united styles, &c. 969. A separate stamen, 

 enlarged. 970. Vertical section of a seed. 



