The Hamamelidae is the second dicot subclass. Unifying characters: usually woody (a few are herbaceous); primary wind-pollination; flowers small, not showy, often in catkins, often unisexual; fruit typically one-seeded. Catkin= spike-like, drooping inflorescence with unisexual, usually apetalous flowers (often without perianth at all). Catkins also called aments, hence the nameAmentiferae for the subclass.
 

Woody

1. Fagaceae-large component of many forests; catkins, fruit a nut subtended by bracts. Ex.: Quercus (Oak)-fruit an acorn; and Fagus (Beech)
 

2. Juglandaceae-fruit a nut enclosed by bracts, pinnately compound leaves. Ex.: Juglans (Walnut) and Carya (Pecan, Hickory)
 

3. Ulmaceae-no catkins, flowers sometimes perfect; leaves simple, often with oblique bases; fruit samara or drupe. Ex.: Ulmus (Elm)-fruit a samara, leaves often doubly serrate; Celtis (Hackberry) -fruit a drupe
 

4. Moraceae-often with milky sap, fruit multiple, leaves simple. Ex.: Morus (Mulberry), Ficus (Fig), Maclura (Horseapple or Bois d'Arc)
 

5. Betulaceae-often of damp places, both sexes of flowers in catkins, leaves simple, fruit a nutlet. Ex.: Betula (Birch) and Alnus (Alder)
 

Herbaceous
 

1. Urticaceae-some with stinging hairs, many with fibrous stems. Ex.:  (Nettle) with stinging hairs; Boehmeria (Ramie) source of fiber
 

2. Cannabaceae-plants often dioecious, some with fibrous stems. Ex.: Cannabis (Hemp, Marijuana) and Humulus (Hops)-flavoring in beer

Back to the Hamamelidae exercise

last modified Sept. 27, 2000 by MDR