THE PEDIGREE OF WHEAT. 673 



rical, for the outer one is simple and convex, while the inner one is 

 apparently double, being made up of two pieces rolled into one, and 

 still possessing two green midribs, which show distinctly like ribs on its 

 flat outer surface. Here, it will immediately be apparent, the traces 

 of the original trinary arrangement are very slight indeed. 



But when we come to inquire into the rationale and genesis of 

 these curiously one sided flowers, it is not difficult to see that they 

 have been ultimately derived from trinary blossoms of the rush-like 

 type. The first and most marked divergence from that type, for 

 which the analogy of the sedges has already prepared us, is the reduc- 

 tion of the ovary to a single one-seeded cell, whose ripe, fruity form is 

 known as a grain. At one time, we may feel pretty sure, there must 

 have existed a group of nascent grasses, which only differed from the 

 wood-rush genus in having a single-celled ovary instead of a three- 

 celled pistil with one seed in each cell ; and even the ovary of this 

 primitive grass must have retained one mark of its trinary origin in 

 its possession of three styles to its one grain, thus pointing back (as 

 most sedges still do) to its earlier rush-like origin. That hypothetical 

 form must have had three sepals, three petals, six stamens, and one 

 three-styled ovary. But the peculiar shape of modern grass-flowers is 

 clearly due to their very spiky arrangement along the edge of the 

 axis. In the wood-rushes and the sedges, we see some approach to 

 this condition ; but in the grasses, the crowding is far more marked, 

 and the one-sidedness has accordingly become far more conspicuous. 

 Suppose we begin to crowd a number of wind-fertilized lily-like flowers 

 alon^ an axis in this manner, taking care that the stamens and the 

 sensitive feathery styles are always turned outward to catch the breeze 

 (for otherwise they will die out at once), what sort of result shall we 

 finally get ? 



In the first place, the calyx, consisting of three pieces, will stand 

 toward the crowded stem or axis in such a fashion that one piece will 

 be free and exterior, while two pieces will be interior and next the 

 stem, thus : 



O 



a a 



a 



Now, the effect of constant crushing in this direction will be that the 

 two inner calyx-pieces will be slowly dwarfed, and will tend to coalesce 

 with one another ; and this is what has actually happened with the 

 inner pale of wheat and of other ojasses, though the midribs of the 

 two originally separate pieces still show on the compound pale, like 

 dark-green lines down its center. Thus, in the fully developed grasses, 

 in place of a trinary calyx, we get two chaffy scales or pales, the outer 

 one representing a single sepal, and the inner one, which has been 

 dwarfed by pressure against the stem, representing two sepals rolled 

 vol. xxii. 43 



