Transcript Commelinaceae -- the spiderwort family (42-50/500

Monocots II
Commelinaceae -- the spiderwort family (42-50/500-700; cosmopolitan)
Habit herbs; somewhat succulent and with mucilaginous sap; stems somewhat jointed with
swollen nodes
Leaves alternate; simple; leaf bases with closed sheath surrounding stem; parallel venation;
with or without pseudopetiole
Inflorescences basically a panicle or 1-many scorpioid cymes (i.e. a “thyrse” in the
literature), each subtended by one or more boat-shaped spathes; sometimes
appearing umbelliform because the main axis is reduced to only 1-2 scorpoid cymes
fused back to back
Special floral characters stamen filaments sometimes ornamented with long trichomes;
flowers colorful
Calyx 3 sepals distinct or connate
Corolla 3 petals distinct (connate)
Androecium 6 (1-3) stamens, distinct (rarely filaments connate) often 1 or more reduced to
staminodes
Gynoecium 3 (2) carpels, connate; superior with 3 (2) locules and 1-few axile ovules;
style 1, undivided
Fruit= capsule (rarely a berry)
(Floral formula: Ca
3
Co
3
A
3+3
G
3
)
Monocots II
Commelinaceae -- comments
Genera: Tradescantia (spiderwort), Zebrina (wandering jew), Commelina
(dayflower), Rhoeo (boat-flower, oyster-plant), Gibasis (bride’s veil),
Geogenanthus (the seersucker plant), Setcreasea (purple heart), Callisia.
Comments: Only important as an ornamental, this family is nonetheless a
hardy houseplant, and in some mild areas, has escaped to become a weed.
The flowers in this family are insect pollinated, but do not produce nectar.
The pollen is the reward, and since a lot of pollen has to be produced to
supply enough for both pollination and the pollinator, it is believed that this
family may be part of a trend that culminated in wind-pollination.
Monocots II
Poaceae (Gramineae) --
the grass family (650-660/10,000; cosmopolitan)
Habit herbs, shrubs or trees; rhizomatous or stoloniferous; stems mostly round with swollen
nodes, mostly hollow (sometimes a pith); intercalary meristems
Leaves alternate or basal; simple; two ranked; leaf bases with open sheath surrounding
stem, upper margins of the sheath may bear small ear-like apical lobes called auricles;
parallel venation; ligulate; blades flat or absent
Inflorescences spikes and spikelets that are 2º clustered into inflorescences (spikes,
racemes, or panicles); each spikelet subtended by 2 basal bracts (glumes), then within
the spikelet, each flower subtended by two bractlets (lemma to the outside and palea
to the inside) all attached to the rachilla
Special floral characters lodicules are interpreted as reduced perianth parts; windpollinated; glumes or lemma can be ornamented with awns
Perianth 2 (3) lodicules distinct, fleshy and becoming turgid at anthesis
Androecium 3 (1-2 or 4-6) stamens, distinct (rarely filaments connate in groups)
Gynoecium 3 carpels (only 2 apparent), connate; superior with 1 locule and 1 basal ovule
usually adnate to ovary wall; styles 2 (1 or 3), distinct or united
Fruit= caryopsis (achene, utricle, nut, or drupe), often shed from the plant together with the
enclosing bracts
(Floral formula: A
3
G
2
)
Monocots II
Poaceae (Gramineae) --
comments
Genera: Triticum spp. (wheat), Avena sativa (oats), Zea mays (corn), Oryza
sativa (rice), Saccharum officinarum (sugar cane), Hordeum vulgare (barley),
Sorghum bicolor (sorghum), Secale (rye), Bambusa spp. (bamboo)
Comments: Without a doubt, the most important family in the average
human’s life! If aliens were to land on this planet and take a quick look around,
they would probably describe a planet in which the grasses had millions of
human slaves tending to their every need...
Rice feeds more humans than any other grain. “Wild rice” is actually a different
species (Zizania aquatica) and is native to North America. Wild rice has a bit
more, nutrition-wise, than rice, but the bracts are harder to separate from the
fruit, and is more expensive to harvest.
As well as the grains that we eat, grass is very important as fodder for many of
our livestock. Range management has become very important in the West (after
overgrazing and catastrophic droughts killed lots of cattle in the past), and you
can take courses that concentrate only on grasses!!
Monocots II
Poaceae (Gramineae) --
comments
Comments: Several species of bamboo (Bambusa sp.), are used not only as
food, but also for timber, pulp, and utensils. Some bamboos grow
vegetatively for years (up to 150 yrs), flower, and then die. This has caused
problems in the past (particularly for pandas) because clones can spread over
large areas of land, and when it is time for that plant to flower all the clones
simultaneously flower and die.
Ornamental uses for grasses include turf-grasses (billions and billions of
dollars are spent on residential and commercial lawns every year) such as St.
Augustine grass and Bermuda grass (Cynodon sp.), and as accent plants in
perennial borders and the landscape.
Fermented grains are the main source of many alcoholic beverages, and some
anthropologists have theorized that these recreational drinks may have had a
profound effect on the beginnings of agriculture!
Monocots II
Cyperaceae -- the sedge family (70-100/4000-9300; cosmopolitan)
Habit herbs (rarely shrubs), often semiaquatic; rhizomatous; stems are typically triangular,
internodes filled with pith
Leaves alternate or basal; usually three-ranked; simple and entire; leaf bases with closed
sheath surrounding stem; linear, parallel venation; ligulate or eligulate; blades flat,
terete, triangular or absent
Inflorescences one to many spikelets aggregated into clusters (racemose, paniculate, often
umbels). Each spikelet organized on a central rachilla to which the bracts/flowers are
attached. Flowers subtended by a bractlet and perianth reduced to bristles or absent
Special floral characters the gynoecium in Carex (and a few close relatives to Carex) is
surrounded by a second bract termed a perigynium that is a hollow, sac-like structure
Perianth reduced to bristles (rarely scales) or absent
Androecium 1-3 (4-many) stamens, distinct
Gynoecium 2 or 3 carpels, connate; superior with 1 locule and 1 basal ovule; style 1, with 2
or 3 branches
Fruit= achene
(Floral formula: A
3
G
2 or 3
)
Monocots II
Cyperaceae -- comments
Genera: Cyperus, Carex, Scirpus, etc.
Comments: A “grass-like” family that is easily separable from Poaceae
based on floral and vegetative characters. Carex is the largest genus, a
taxonomic nightmare with over 3000 species and incredible variation. If you
ever want a real challenge, try to key some of these out!
Cyperus papyrus (Papyrus) was used to make one of the early types of paper,
and today it is still the toughest paper made. The family contains many
ethnobotanically important members including: Cyperus used for making
mats in Asia, Cladium used for making thatched houses in Europe, and
Scirpus used as medicinals, as well as many others.
Chinese water chestnuts are slices of corms harvested from Eleocharis
tuberosa.