8 BULLETIN 289, U. S. DEPARTMENT OF AGRICULTURE. 
(fig. 2, B). The stigmatic surface is papillate and has a fringed 
appearance in the mature flower. The papille contain much oil and 
have rather heavy walls, which react to the test for cutin. 
Both ovules develop embryo sacs (fig. 2, C). Fertilization usually 
takes place in each ovule; but only one, so far as observed, matures 
into a seed. Should plants occur that mature both ovules, there 
would be an opportunity to produce strains with twice the seed- 
yielding capacity of those now grown. 
Fic. 2.—Red-clover flowers, showing different stages of development. A.—Lengihwise section of a red- 
clover flower at an early stage (X50): a, Calyx tube; b, staminal tube; c, standard; d, one of the long 
stamens; ¢€, anthers of two long stamens; /, free stamen; g, stigma; h, the two ovules; 7, anther of a short 
stamen; j, stylar canal. B.—Lengthwise section of an open flower, showing the character of the stigma 
and its position relative to the anthers (25): a, Stigma; 6, anthers of two long stamens; c, anthers of 
two short stamens. C.—Lengthwise section through the base of a flower, open and ready for fertilization 
(x40): a, Egg; b, endosperm cell; c, calyx; d, staminal tube; e, nectar glands; f/, free stamen. D.—A 
median, longitudinal section through the nucellus of a sterile ovule which should have been ready for 
fertilization, the flower being open; all cells remained vegetative and no reproductive cells were produced 
(x18). E.—Pollen grain (325): g, Germ pore; n, nucleus; w, wall. 
INFERTILE OVULES OF RED CLOVER. 
Infertile ovules are a common occurrence in red clover and occur to 
a considerable extent throughout the season. A section through the 
nucellus of an infertile ovule is shown in figure 2, D. In the infertile 
ovules all cells remain vegetative and no embryo sac is formed. The 
largest percentage of infertility has been found to occur in first-crop 
red clover, and this infertility appears to accompany moist soil and 
atmospheric conditions. During the first crop many plants produce 
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