Lecture 28: Monocots: Poaceae Flashcards
Class Liliopsida
65,000 species 11 orders
Phylogenetically the Acorales are what in relation to monocots
Acorales is sister to all remaining monocots
[Genus Acorus (sweet flag)]
family Alliaceae (need to know)
onion, garlic, chives, leek
Agavaceae (need to know)
agave
Asparagaceae (need to know)
asparagus, order Asparagales
Asphodelaceae (need to know)
aloe
Hyacinthaceae
hyacinth
Iridaceae
iris, crocus, gladiola
Orchidaceae
largest family of monocots, Genus Vanilla
Discoreaceae
yam (common crop in africa) and birth control pill
Liliales
Liliaceae (lilly and tulip)
Zingiberales families (need to know)
Musaceae –bananas Zingiberaceae–ginger
Smilacaceae (need to know)
greenbriar gives us sarsaparilla
Musaceae
bananas
Zingiberaceae
ginger
Order Poales
17 families
Eriocaulaceae (pipewort)
Xyridaceae (yellow-eyed grass)
Bromeliaceae (bromeliad—pineapple)
Typhaceae (cattail)
juncaceae (rush)
Cyperaceae (sedge)
Flagellariaceae (flagellaria)
Restionaceae (restio)
Joinvilleaceae (joinvillea)
we focus on the type family Poaceae
Bromeliaceae
pineapple
Family Poaceae
the grass family AKA Gramineae (latin for grass) 9.500 species, 668 genera 4th largest family of flowering plants
Grass leaves
alternate and 2-ranked attached on 2 sides of stem
1) sheath is attached at the node and envelops the stem above the node
2) leaf blade extends away from the stem and is typically flat and narrow with parallel venation
Intercalary meristem at base
Intercalary meristem
at base, which allows leaves of grasses to keep growing even if tip is removed
Clum
upright stem of grasses,
initially has short internodes
later tip emerges from 2-ranked nested leaf-sheaths internodes
resume growth via intercalary meristem located above each node
Clum then telescopes up into wind
Sod
perrennial grasses germinate to form a sod (dense mat of individuals) sod is held together by the rhizomes and the fibrous root system think of sodding the lawn
Tussock
like a sod but a clump with short rhizomes that produce upright branches (tillers) at base of plant
Tillers
Uprigh branches at the base of grasses produced by rhizomes
Grass inflorescence
simple subunits called spikelets at base,
there are 2 nodes with bracts that are sterile (flowers not produced at these nodes)
stem that forms the axis is called rachilla
a fertile bract attached to the node of the rachilla is called a lemma (husk)
bract at base of pedicel is palea (chaff)
Spikelet
highly condensed branch of inflorescence with sterile bracts at base
called the 1st and 2nd glume
stem that forms the axis is called rachilla
a fertile bract attached to the node of the rachilla is called a lemma (husk)
Lemma
a fertile bract attached to the node of the rachilla
lemma encloses palea;
palea encloses flower
palea
bract at the base of the pedicel lemma encloses palea; palea encloses flower
Grass inflorescence
each spikelet has 2 glumes at the base and 2 ranks of lemmas along the rachilla
with each lemma enclosing a palea, which encloses a single flower
Grass Flowers
perfect, hypogenous, actinomorphic
Protoandrous
Perianth reduced (2-3 scale tepals called lodicules)
3 differentiated stamens compound pistil,
superior ovary 2-3 styles (usually 2, with 2 carpels)
lodicules
scale like tepals in grasses
Floret
lemma+palea+flower unit
(kind of a misnomer) lemma and palea are derived from bracts,
not the 4 floral series.
functionally, lemma and palea are part of the floral unit
Fruit of grasses
grain (caryopsis)
1-seeded, dry, indehiscent fruit
pericarp fused to seedcoat
development of fruit in grasses
embryonic sporophyte develops towards the side of the seed closest the lemma
embryo is the germ of wheat,
corn and grains fusion of matured ovary wall (pericarp) to the coat makes a bran \
Dobule fertilization produces endosperm
bran
structure formed when pericarp fuses to seed coat as in grains, the fruit of grasses aleurone layer of cells just inside the bran
endosperm
nutritive tissue used by the developing embryo during germination and seedling establishment contains starch, proteins, fat, vitamins
aleurone layer
cells just inside the bran rich in proteins and fats at germination, the layer secretes the enzymes that break down the endosperm starch into sugars that are absorbed by the germinating embryonic sporophyte
Haustorium
What 1 cotyledon in grass is called after it is modified by absorbing sugars released from the endosperm and transporting them to the sporophyte via phloem called scutellum in grasses
Polishing/pearling
Industrial removal of aleurone layer of cells inside the bran (which are cells that break down endosperm)
this leaves only the starchy endosperm makes white flower and rice,
which has a long shelf life grains with germ have oils in embryo that become oxydized,
esp. if they are crushed or ground up, tend to go rancid.
but provide more balanced nutrition
Grass Pollination
When flower is almost mature, lodicules swell,
separating the lemma and palea filaments
elongate 1st so anthers emerge and release pollen
styles then elongate,
placing feathery stigmas into the wind to catch pollen as it passess
Protoandrous flowers promote cross pollination
Rushes, Sedges, Grasses
The difference between Junaceae (rush) , Cyperaceae (sedge) and Poaceae (grass)
Rush stems are round in cross section with solid internods
Sedge stems are triangular with solid internodes
Grass stems are round with hollow internodes and flexible nodes that serve as joints
Rushes are round, sedges have edges, and grass comes in joints
Significance of Grass (need to know) all in Poaceae family
cereals: wheat, barley, oats (near eastern cultures)
rice (far east staple)
sorghum and pearl millett (African)
corn/maize (new world cultures)
70% of our farms are crop grasses, 50% of our calories come from grasses
make breakfast cereals, breads, tacos, rice
Important derivatives: corn starch, corn sweeteners, corn oil (margarine), livestock feed off grains
Grown for sap: sugar cane (white sugar) molasses from stem of sorghum
cereals
grasses grown for their edible seeds
Barley malt
makes beer
malt–germinated grain in which enzymes released from the aleurone layer have converted starch into sugars
these are fermented using a fungus
sake
rice wine, but really more like rice beer
starts with polished rice (lacks aleurone layer)
starch converted to sugars using 2 fungi! (so higher alc %)
Aspergillus and cerevisiae fungi
Other Alcohol?
Rye, Corn, potato
whiskey made from barley
rye (secale cereale) makes rye whiskey
corn used to produce bourbon
gin/vodka highly distilled from barley, grains, and potatoes (solanaceae)
Gin is flavored with Cupressaceae juniper ovulate cones
Rum is distilled from fermented sugar can/molasses
Other economic uses of grasses
Tussock Grasses as ornamentals in lawn/garden
bamboo used for houses, building and for matting for beds
bamboo also used for eating (youmg shoots only), fiber for paper, and pulp for rayon
Bamboo
Height achieved by primary plant body due to structural organization of stem:
strong fibers at perimeter, hollow internodes, enlarged, flexible nodes, that serve as joints to positiion the stem segments
Segmented, hollow tube is strong, lightweight, and flexible
This organization is similar (but altered) for many grasses
bamboo used for houses, building and for matting for beds
bamboo also used for eating (youmg shoots only), fiber for paper, and pulp for rayon
