GRASSES OF OHIO 257 



Phylum, Anthophyta, flowering plants. Seed plants of diverse habit and com- 

 monly with showy flowers on the sporophyte, with closed carpels or carpel sets, 

 with female gametophytes of eight or rarely sixteen, or a smaller number of cells, 

 usually containing two, or rarely more, polar nuclei which conjugate with each 

 other and with one of the two nonmotile sperms from the male gametophyte or 

 pollengrain, which is deposited on a stigma and develops a long pollentube. As the 

 result of this triple fusion a new tissue is produced of greater or less extent sur- 

 rounding the developing embryo in the ovule. This peculiar endosperm is called 

 the xeniophyte generation and it is the presence of this tissue, especially, in many 

 grains of grasses that gives them their great food value. 



The grasses belong to the class Monocotylae, or monocotyls, which 

 may be defined as having the following characteristics : 



Sporophytes developing as herbs or sometimes as woody plants of large 

 dimensions ; embryo usually with one terminal cotyledon and a lateral plumule ; 

 stem with closed, usually scattered vascular bundles, without typical bark and 

 annual rings of growth,, rarely with secondary thickening ; leaves mostly parallel- 

 veined, sometimes netted-veined ; flowers more commonly trimerous, the ideal 

 being a trimerous, pentacyclic flower with united carpels. 



The Monocotyls are divided into four subclasses, the grasses falling 

 into the subclass, Ghtmiflorae: 



Glumiflorac (Glume-flowered Monocotyls). Usually grass-like herbs or some- 

 times woody plants with hypogynous, inconspicuous flowers. Carpels united ; 

 stigmas 3-1 ; perianth usually of 6-2 minute segments or bristles or entirely want- 

 ing; inflorescence usually consisting of spikes or spikelets variously clustered; 

 endosperm mealy, starchy or rarely sugary. 



The order of the Glumiflorae to which the grasses belong is com- 

 monly called Graminales and is characterized by its unilocular ovulary 

 containing one anatropous, erect or ascending ovule. 



There are two families of Graminales, Cyperaceae or Sedges and 

 Graminaccae or Grasses. In general the sedges constitute the lower and 

 less specialized group. 



Graminaceae. Grass Family 



Highly specialized, perennial, geophilous herbs or annuals, or sometimes woody 

 plants, with hollow or occasionally solid stems, having prominent internodes, the 

 nodes closed. Leaves 2-ranked, with sheaths, the sheaths usually split to the base; 

 upper end of the sheath usually with one or two ligules ; sometimes with a short 

 petiole between the sheath and the blade, in which a cleavage plane is developed. 

 Inflorescence a panicle, raceme, or spike, composed of spikelets. Spikelets and 

 flowers with 2-ranked glumes, each spikelet normally with two empty glumes at 

 its base and each flower normally with two flowering glumes, the outer one called 

 the lemma, the inner the palet. Flowers bisporangiate or monosporangiate, mone- 

 cious or diecious with all intermediate gradations, often completely vestigial. 

 Perianth of 3 usually 2 small bracts called lodicules which probably represent a 

 corolla or inner perianth cycle; stamens of the andrecium 6, or usually 3. some- 

 times reduced to 2 or 1 ; anthers versatile, with 4 microsporangia ; gynecium highly 

 specialized, consisting of 3 united carpels forming a unilocular ovulary with one 

 ovule ; stigmas 3, 2 or 1, usually 2, hairy or plumose. Fruit a dry seed-like grain 

 (caryopsis), or in the lower forms sometimes fleshy; endosperm starchy or rarely 

 sugary. 



