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Hamamelidae
Hamamelidaceae -- the witch hazel family
(26/100; widely distributed,
esp. in eastern Asia and eastern North America)
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 -- comments
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
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)
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 -- comments
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
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)
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
)
Hamamelidae
Fagaceae -- comments
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
Moraceae -- the mulberry or fig family
(40-70/1,000-2,500; primarily tropical,
although Morus and Maclura are common in temperates)
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 -- comments
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!!
ß-family Hamamelidae
Ulmaceae -- the elm family
(15-18/150; Temperate to tropical; especially in the
Northern Hemisphere)
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
)