284 APETALOUS OEDERS. 



625. Salicace^j the Willow Tribe. — Trees or shruls. Learns 

 alternate, simple, stipulate. Floioers dia^cioiis, amentaceous, 

 and destitute of tloral envelopes, or with a membraneous cup 

 like calyx. Stamens distinct or monadelplious. Ovary l-celled; 

 ovules numerous, erect ; stigmas 2 or 4. Fruit coriacooas, 

 l-celled. Seeds numerous, small, covered with a silkj coma, 

 exalbuniinous. 



a. Properties : the bark is usually astringent and tonic. 

 Gexeha. — Salix, Populus. 



526. Balsamiflu^, tlie Sweet- Gum Trihe. — Trees. Lea/ves 

 alternate, simple or lobed, stipules deciduous. Flowers monoe- 

 cious, amentaceous. Catkins or heads roundish. Anthers nu- 

 merous, nearly sessile, destitute of floral envelopes. Ovaries 

 2-celled, each surrounded by a few scales. Fruit a cone com- 

 posed of hard, connected scales, in the cavities of which lie 

 2-lobed, 2-celled capsules. Seeds numerous, winged, albumi- 

 nous. 



a. Properties : the bark is hot, bitter, and stomachic ; a fragrant resin is yielded 

 by several species. 

 Genus. — Liquid amber 



527. Platanace^, the Plane-tree Trihe. — Trees with a watery 

 juice. Leaves alternate, palmate. Flowers monoecious, amen- 

 taceous, naked. Catkins round, pendulous. Stamens mixed 

 w^ith small scales. Ovary l-celled ; style thick, subulate. Nuts 

 clavate, compressed. Seeds 1-2, pendulous, albuminous. 



Genus. — Platanus. 



528. Ueticace^, the Nettle Trihe. — LLerls^ shruhs, or trees. 

 Leaves alternate, stipulate, covered with stinging hairs. Flowers 

 monoecious, dioecious, or polygamous, scattered, or collected 

 into catkins or heads. Calyx membraneous, lobed, persistent. 

 Stamens inserted into the base of the calyx opposite its lobes ; 

 definite, distinct. Ovary superior ; ovule solitary, erect ; sticjma 

 fringed. Frtiit an indehiscent nut, surrounded by the mem- 

 braneous or fleshy calyx. Emhryo straight, with fleshy albu 

 men. 



a. Properties : excessive causticity in the limpid juice is the chief characteristic. 

 Genera. — Urtica, Parietaria, Datisca. 



Sub-order CANXABiNiE, the LLemp Trihe. — Seeds suspended, 

 destitute of albumen ; embryo hooked or coiled. 



Genera. — Cannabis, Humulus. 



Pig. 206, Humulus lupulvs (hop) ; a represents the pistillate flowers forming 

 oval, drooping, and peduncled green cones or strobilums ; ste7n twining. 



Sub-order More^, the Mulberry Tribe. — Seed solitary, pen-. 

 dulouB, albuminous ; emhryo hooked : guioe milky. 



Genera. — Morus, Broussonetia, Ficus. 



