312 



BOTANY. 



ous. and the gynoecium itself superior (Fig. 311). Sometimes the 

 growth of the broad flower-axis stops at its apex long before it does 

 so in its marginal portions ; a tubular- ring is thus formed, carrying 

 up calyx, corolla, and stamens, which are then said to be perigynous, 

 and the gyncecium half inferior. These terms are used also in the 

 cases where the gyncecium is similarly surrounded by the tubular 

 sheath composed of adnate calyx, corolla, and andrcecium. In some 

 nearly related cases, in addition to the structures described above as 

 perigynous, there is a complete fusion of the calyx, corolla, and 



Fig. 211. Fig, 212. 



Fig. 211.— Flower of Shepherd's-purae (Bursa), with superior ovary, and 

 hypogynous stamens and perianth. 



Fig. 212.— Flower of Watermelon, with inferior ovary, and epigynons 

 perianth. 



stamen-bearing tube with the gyncecium, so that the ovule-bearing 

 portion of the latter is below the rest of the flower. The perianth 

 and the stamens are said to be epigynous in such flowers, and the 

 ovary is inferior. (Fig. 312.) Some cases of epigyny are doubtless 

 to be regarded as due to the adnation of the calyx, corolla, stamens, 

 and ovaries ; in others the ovaries are adnate to the hollow axis 

 which bears the perianth and stamens. 



Certain terms descriptive of relations between the stamens and 

 pistils which have recently come into use require explanation here. 



Relative Terms — In many flowers the stamens and pistils do not 

 mature at the same time — such are said to be dichogamous ; when 

 the stamens mature before, the pistils the flower is proterandrous • 

 and when the pistils mature before the stamens they a.ie proterogynous. 



