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Habit shrubs or trees Leaves alternate, simple, stipulate Inflorescences solitary or clustered axillary flowers, heads or spikes Special floral characters flowers regular, hypanthium present or absent, ± adnate to ovary Calyx 4-5 (0) sepals connate; usually ± adnate to ovary Corolla 0 (4-5) petals distinct Androecium 4-5 (2-many) stamens, distinct and alternate to petals Gynoecium 2 carpels; connate usually at the base; superior to inferior (often half-inferior); 2 locules with 1-many axile ovules; 2 styles Fruit= woody capsule (can appear like a follicle if one carpel aborts) (Floral formula: Ca 4-5 Co 0 A 4-5 G 2 ) Hamamelidae Hamamelidaceae -- the witch hazel family (26/100; widely distributed, esp. in eastern Asia and eastern North America)
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Comments: A variable and probably paraphyletic assemblage of trees & shrubs. Flowers range from insect-pollinated showy flowers with petals to wind-pollinated with reduced or absent perianth. Unifying characters relative to others of the Hamamelidae: the 2 basally-fused carpels and woody capsular fruit. Members include Hamamelis (witch hazel extract from dried leaves and twigs of H. virginiana), Liquidambar (sweet gum), Fothergilla (witch-alder), Corylopsis, and more. Several genera are used for lumber. Hamamelidae Hamamelidaceae -- comments
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Habit shrubs or trees Leaves alternate, simple, stipulate Inflorescences both staminate (with 2-3 flowers) and pistillate (with 1-3 flowers) inflorescences as cymules subtended by scale-like bractlets in catkins: pistillate catkins not as elongate and pendulous as staminate catkins Special floral characters flowers always imperfect and always in catkins, when the calyx fused to the extent that it is not visible, the pistillate flower is called nude and appears superior, but is actually inferior Calyx of pistillate flowers: 2-4 (0) sepals very reduced; connate and adnate to ovary Calyx of staminate flowers: 2-4 (-6) sepals distinct Corolla absent Androecium 2-6 (-8) stamens, distinct or filaments basally connate Gynoecium 2 carpels; connate; superior (appears that way in nude flowers) to inferior; 1-loculed above, 2-loculed below with 1 axile ovule/locule; 2 styles Fruit= achene, nut or samara (Floral formulas: Ca 2-6 A 2-20 AND G 2 OR A 2-8 AND Ca 2-6 G 2 ) Hamamelidae Betulaceae -- the birch or alder family (6/120-170; mostly cool-temperate regions of Northern Hemisphere but extending southward in montane habitats to the Andes)
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Comments: A fun family of trees and shrubs of the cold temperates to subartic regions of northern hemisphere. Often associated with streams, lakes or poorly drained areas. Distinguished from others in the Hamamelidae by possessing pistillate flowers in catkins. Well-known members include Betula (birch; flavoring for birchbeer), Alnus (alder), Carpinus (horn-beam, ironwood), Ostrya (hop-hornbeam), Corylus (hazelnut, filbert). Wood of some birches valuable for furniture, flooring and cabinetry. Bark of B. papyrifera was used by some N. American natives to make canoes. This papery bark makes getting fires started on camping trips alot easier too. Hamamelidae Betulaceae -- comments
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Hamamelidae Habit shrubs or trees Leaves alternate, simple, stipulate with caducous stipules Inflorescences staminate inflorescence an erect or pendulous spike or head; pistillate inflorecence of 1-3 (-7) flowers subtended by a cupule of numerous ± connate bractlets Special floral characters flowers always imperfect, staminate inflorescences in catkins or spikes, pistillate flowers (or flower) subtended by a cupule Calyx of pistillate flowers: 2-8 sepals very reduced; connate and adnate to ovary Calyx of staminate flowers: 2-7 sepals connate Corolla absent Androecium 4-many stamens distinct Gynoecium 3-7 carpels; connate; inferior; 3-7 locules with 2 axile ovules/locule; styles as many as carpels Fruit= nut subtended or surrounded by a woody cup-like or bur-like cupule (Floral formula: Ca 2-7 A 4- AND Ca 2-8 G 3-7 ) Fagaceae -- the beech and oak family (9/1000; Worldwide temperate with a few tropical; important member of northern temperate habitats and some montane tropical habitats)
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Comments: Some claim that the family contains the most biomass of any dicot group, hinting at the dominance this group displays in many temperate and montane tropical habitats. The wood is extremely valuable as lumber, firewood, etc. Edible nuts come from Castanea, Fagus, and Quercus (if leached of tannins). Lithocarpus and some others are commercial sources of tannins. The cupule, found subtending or enveloping the pistillate flower or flowers in all members of this family, is a very unique characteristic of this family. The latest theory is that this structure is a highly reduced branching system, and is all that remains of a much larger pistillate inflorescence. Involucres are composed of bracts that are modified leaves (remember the family Asteraceae?). Because the “bracts” that subtend or surround the pistillate inflorescence in the Fagaceae are interpreted to be part of a reduced branching system, it is more accurate to call this structure a cupule. Hamamelidae Fagaceae -- comments
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Habit shrubs or trees (herbs) often with milky latex Leaves alternate, simple, stipulate with caudacous stipules that leave a circular scar Inflorescences variable, ranging from spike-like or raceme-like in Morus to the inside-out syconium in Ficus Special floral characters flowers imperfect, sometimes on a fleshy receptacle Calyx (2) 4 (6) sepals distinct; inconspicuous; usually free or adnate to ovary Corolla absent Androecium (2) 4 (6) stamens, distinct and opposite to sepals Gynoecium 2 carpels; connate; superior to inferior; 1 locule with 1 apical ovule (rarely 2-3 locules and 1 apical/axile ovule/locule or just one ovule in one of the locules); 2 styles Fruit= achene or drupelet, often coalescent into a dense multiple fruit with accessory tissues (Floral formula: Ca 4 A 4 AND Ca 4 G 2 ) Hamamelidae Moraceae -- the mulberry or fig family (40-70/1,000-2,500; primarily tropical, although Morus and Maclura are common in temperates)
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Some Genera: Morus (mulberry); Maclura (osage-orange); Ficus (fig), Artocarpus (breadfruit, jackfruit) Notes: Ficus (800+ spp.) is a very large genus with milky latex, a variety of habits, and some tasty syconiums (the fig “fruit”). A must see is the inflorescence of the genus Dorstenia to get an idea of a transformation series from the mulberry- type (spike) to the Dorstenia-type to the fig-type (syconium) inflorescence. Read W&K about the special pollination syndrome that is associated with the inflorescence of figs. It is interesting to know that although the ancient Romans did not know about the wasps and this pollination syndrome, they noticed that if they planted new fig trees too far away from established figs, they did not were not able to get fruit set on those newly planted, isolated fig trees!! Hamamelidae Moraceae -- comments
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Habit shrubs or trees, leaves often asymmetric at the base Leaves alternate, simple, stipulate Inflorescences solitary or clustered axillary flowers Special floral characters superior ovary Calyx 4-8 sepals distinct or basally connate Corolla absent Androecium 4-8 stamens, distinct; opposite and sometimes adnate to the sepals Gynoecium 2 carpels; connate; superior; 1 locule with 1axile ovule; 2 styles sometimes winged or forked Fruit= samara or drupe (Floral formula: Ca 4-8 A 4-8 G 2 ) ß-family Hamamelidae Ulmaceae -- the elm family (15-18/150; Temperate to tropical; especially in the Northern Hemisphere)
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