Alnus: A plant genus of the family BETULACEAE that is distinguished from birch (BETULA) by its usually stalked winter buds and by cones that remain on the branches after the small, winged nutlets are released.Betulaceae: A plant family of the order Fagales, subclass Hamamelidae, class Magnoliopsida. They have simple, serrate, alternate leaves. Male flowers are borne in long, pendulous catkins; the female in shorter, pendulous or erect catkins. The fruit is usually a small nut or a short-winged samara.Diarylheptanoids: A group of compounds consisting of two aromatic rings separated by seven carbons (HEPTANES) and having various substituents. The best known member is CURCUMIN.Frankia: Genus of BACTERIA in the family Frankiaceae. They are nitrogen-fixing root-nodule symbionts of many species of woody dicotyledonous plants.Betula: A plant genus of the family BETULACEAE. The tree has smooth, resinous, varicolored or white bark, marked by horizontal pores (lenticels), which usually peels horizontally in thin sheets.Corylus: A plant genus of the family BETULACEAE known for the edible nuts.Elettaria: A plant genus of the family ZINGIBERACEAE, order Zingiberales, subclass Zingiberidae. Elettaria cardamomum (L.) Maton is the source of Cardamom used in SPICES.