GRAMINEAE. 249 



sepals, the third sepal having entirely aborted. Rudiments of 

 this third sepal are present in some of the gramineae. 



405. Other members of the grass family. To the gramineae 

 belong also the wheat, barley, corn, the grasses, rice, etc. It 

 is one of the most important families from an economic stand- 

 point, furnishing a great variety of food for man and other 

 animals. The gramineae, while belonging to the class mono- 

 cotyledons, are less closely allied to the other families of the 

 class than these families are to each other. For this reason 

 they are regarded as a very natural group. 



Exercise 67. 



406. The wheat (Triticum sativum vulgare). The wheat plant may be 

 studied as an alternate for the oat plant. 



The entire wheat plant. Study the entire wheat plant, and compare with 

 the oat plant. Are the stems of the wheat single or are stools formed? 

 Since a germinating grain of wheat forms at first but a single stem, how are 

 the stools formed ? Examine young wheat plants to determine this. 



The inflorescence, The " head " of wheat forms a single spike. Sketch a 

 spike. Remove a few of the spikelets, and note the jointed and zigzag char- 

 acter of the axis (rachis) of the spike ; note the attachment of the spikelets. 



The spikelets. Note the empty glumes at the base ; determine how many 

 flowers there are in a spikelet. How many flowering glumes and palets are 

 there to each flower ? In a mature head of wheat determine how many of 

 the flowers in a spikelet ripen grain, and how many are sterile ? Are there 

 any of the spikelets which are completely sterile ? Where are they located ? 



Using a head of wheat at the time of flowering, spread apart the members 

 of a flower with the aid of dissecting needles, and sketch the parts of the 

 flower, showing the glume, palet, the three stamens, and the pistil with the 

 plumose styles. Endeavor to find the lodicules. (See the description of the 

 oat flower for comparison.) 



Sketch an empty and a flowering glume to show the " nerves" and awns. 

 Compare the grain of wheat with a grain of corn. (See paragraph 9.) 



Material. Entire stools of young, fresh plants (may be obtained at any 

 time during autumn, winter, or spring) ; mature plants in flower (if they can- 

 not be obtained fresh they may be dried, preserving at the same time some of 

 the flowering heads in alcohol or formalin) ; ripe heads of wheat. 



