. The natural history of plants. Botany. 234 NATURAL HISTORY OF PLANTS. number, are superposed to them. A liius eoi' Fig. 160. Trifloroua male floriferous scale. ]fig. 161. Male floriferous scale, flowers removed. Earely the flower is 10-12- merous and In the female catkin, ordi- narily shorter, more rigid than in the Birches, and erect, there are only two flowers in the axil of each of the thick scales, the middle one being abortive. The gynsecium is similar to that of the Birches, and the fruit, 'dry and monospermous, is wingless or surrounded by a membranoug wing. T
. The natural history of plants. Botany. 234 NATURAL HISTORY OF PLANTS. number, are superposed to them. A liius eoi' Fig. 160. Trifloroua male floriferous scale. ]fig. 161. Male floriferous scale, flowers removed. Earely the flower is 10-12- merous and In the female catkin, ordi- narily shorter, more rigid than in the Birches, and erect, there are only two flowers in the axil of each of the thick scales, the middle one being abortive. The gynsecium is similar to that of the Birches, and the fruit, 'dry and monospermous, is wingless or surrounded by a membranoug wing. The axillant scales there become woody. The Alders are trees and shrubs of the Ahius giutiiwsa. temperate and cold regions of both worlds in the northern hemisphere, rare in South America and south- ern Africa. Their organs of vege- tation are analogous to those of the Birches. The leaves are accom- panied by lateral stipules. The flowers are sometimes developed at the same time as the leaves, but more frequently earlier, and in this case the females may, as in the species constituting the genus Ahaster,^ emerge from buds bearing one or more leaves. Often the catkins are solitary, more rarely they are collected- in clusters. About flfteen species of Alder are enumerated.* Fig. 165. Side view of male floriferous scale. Fig. 166. Male flower. Fig. 167. Compound fruit. ' In A. nitida Endl. aud nepaknsis Don, of which has heen made the genua Ckthi opsis (Spach, Ann. Sc. Nat. ser. 2, xv. 183, 201). 2 Spach, Ann. Sc. Nat. ser. 2, xv. 200; Suit. a Buffon, xi. 244. 3 Un these grounds Kegel divides the genus into 4 sections: 1. Cletht-opsis (). Flowers developed at same time as leaves. Male scalps uniflorous. Female flower 10-12- merous.â2. Alnaster (Endl.). Flowers pre- cocious. Male catkins coming from 1-3-phyl- lous buds. Scales 3-fiorous. Fruit with membranous wing.â3. PhyUothyrsiu (Spach). Flowers developed at same time as leaves. Scales 3-florous. Floral buds aphyllous. Fr
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1871
