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a family of monoecious, dicotyledonous plants.
Betulaceae are trees or shrubs with alternate leaves and early falling stipules. The flowers are small, plain, unisexual, anemophilous, and gathered into compound, catkin-like inflorescences consisting of extremely vestigial dichasia (two or three flowered). The staminal (male) catkins are pendulous, long, and cylindrical; the pistillate (female) ones are more or less upright, shorter than the staminal ones, and cylindrical or oval. The ovary is on top. The fruit is nutlike, winged, or wingless. There are two genera of Betulaceae: Betula (birch) and Alnus (alder). The number of species is very approximate (because of highly developed hybridization of the birch) but is close to 200. Betulaceae are distributed chiefly in the nontropical regions of the northern hemisphere, but they are also found in southern Asia and in America as far south as Chile and Argentina. Both the birch and the alder are important timber-forming species. Sometimes the hazels are included in the Betulaceae family as a special subfamily.
REFERENCESFlora SSSR, vol. 5. Moscow-Leningrad, 1936.
Winkler, H. “Betulaceae.” In Das Pflanzenreich, fasc. 19. Leipzig, 1904.
M. E. KIRPICHNIKOV