GROUPS AND ORDERS OF APETALOUS EXOGENS. 129 



Geoup 5. Ovary simple, or of 2 - 4 combined carpels. Flowers small, bracteate or involucrate, but usually deititute of 

 calyx and corolla. — Submerged or floating aquatic herbs, 



93. CEaATOPHYLLACEi:. Flowers monoecious, axillary. Stamens numerous : anthers sessile. Ovary one-celled, 



with a single suspended ovule, becoming a beaked achenium in fruit. — Leaves wborled and dissected, 

 with filiform segments. 



94. Cailitrichaceje. Flowers polygamous, axillary, with a calyx-Iikc 2-leaved involucre. Stamen 1 (rarely 2), 



with a slender filament. Ovary 4-lobed, 4-cel!ed, with a solitary suspended ovule in each cell, in- 

 dehiscent in fruit. — Leaves opposite. 



95. Poi)OST£MAC£.s:. Flowers arising from a spathc. Calyx mostly wanting. Stamens often solitary, or if more, 



usually monadclphous. Ovary 2 - 3-cellcd, with as many distinct styles as cells. Capsule ribbed, 

 with numerous seeds. — Leaves mostly cut into capillary segments. 



Gsoirp 6. Flowers monoecious or dioecious, sometimes furnished with both petals and calyx, but often destitute of both, 

 not amentaceous. Ovary 2 - several-celled, with one or two ovules in each cell. Fruit capsular or drupa- 

 ceous, with two or more cells. 



96. EiiFHOB.BiA.czM. Calyx free from the ovary, sometimes none. Corolla very often wanting the petals ; when 



present, distinct. Styles distinct. Fruit capsular, separating into several (often three) carpels or 

 cocci, which open elastically by one or both sutures. — Juice often milky. 



97. Empetbaceje. Calyx consisting of imbricated sepals. Stamens few, as many as the inner sepals. Ovary 



free, 2 - 9-celled, with a single erect ovule in each cell. Fruit drupaceous (sometimes dry), with 

 2-10 bony nucules. 



Obottp 7. Flowers monoecious or dioecious ; the sterile and often the fertile also in aments, or in heads or spikes, either 

 furnished with a calyx or achlamydeous. Ovary one - several-celled, but the fruit always one-celled (except 

 in LiaoiDAMBAR). — Trees or shrubs, except in Ord. 131, many of which are herbs. 



98. JtrOLANPACEJE. Flowers monoecious. Sterile flowers in aments. Fertile flowers few, clustered. Calyx 



adherent. Ovary imperfectly 2 - 4-celled, but with a single ovule. Fruit drupaceous ; the epicarp 

 somewhat fleshy and coherent, or coriaceous and dehiscent. Endocarp bony. Seed oily, without 

 albumen. — Leaves pinnated. 



99. CvTVLmRJE. Sterile flowers in aments. Fertile flowers solitary or clustered, furnished with an involucre 



which at length either includes the fruit, or forms a cup at its base. Fruit a l-celled or 1-seeded 

 nut. Seed without albumen. Cotyledons thick and fleshy. — Leaves simple, 



100. MTElCACEa;. Flowers monoecious, both kinds in aments and achlamydeous. Ovary one-celled, with a single 



ovule. Fruit dry or drupaceous. — Shrubs, with simple leaves, dotted with resinous glands. 



101. BxTULACE£. Flowers monoecious, both kinds in aments and commonly achlamydeous. Ovary 2-ceiled, with 



a single ovule in each cell. Fruit membranaceous or samara-like, one-celled, one-seeded. — Trees 

 or shrubs, with simple leaves. 



102. Salicace£. Flowers dioecious, both kinds in aments and achlamydeous. Ovary hnperfectly 2-ceIled, with 



many ovules : styles or stigmas 2. Fruit follicular, 2-valved. Seeds numerous, with a silky coma. 

 — Leaves simple. 



103. BAtgAMiPLtra:, Flowers monoecious, achlamydeous ; the sterile in conical, the fertile in globose heads or aments. 



Capsules 2-beaked, opening between the beaks, several-seeded, collected with the scales into a hard 

 ball, — Leaves palmately lobed, 



104. PLATANACE.E. Flowers monoecious, in globose heads, achlamydeous. Fruit a one-seeded nut, with bristly 



hairs at the base, collected into a compact ball. — Leaves palmately lobed. 



105. UBTicACEa:. Flowers various, often in aments or fleshy heads. Ovary free from the calyx, with a solitary 



ovule. Fruit an achenium or utricle. 



[Flora — Vol. 2.] 17 



