12 MORPHOLOGY, OR COMPARATIVE ANATOMY. 



is that it contains, and ultimately discharges, the fine dust-like 

 sperm-cells or fertilizing globules called pollen. 



The centre of the flower is occupied by the gyncecium or pistil, 

 the female or seed-bearing part of the flower. Pistils are formed 

 of foliar organs corresponding to sepals, petals, and stamens, and 

 called carpels; but these are not always so readily distinguishable, 

 on account of their varying number and degree of union, conse- 

 quent upon their being crowded at the apex of the flower-stalk. 

 The distinguishing character of a carpel is that it bears ovules or 

 rudimentary seeds containing germ-cells. 



As the stamens furnish the pollen by which the germ-cells are 

 rendered fertile, the two sets of organs, stamens and carpels, are 

 considered essential organs of flowers, without which the purpose 

 of the whole structure could not be performed. 



In some flowers, such as those of the Hydrangea and the Snowball-bush 

 (Viburnum Opulus], there is a tendency in cultivation to the abortion of 

 the stamens and pistils ; so that the flowers become neuter, or totally 

 barren. But in many plants it is the natural condition for the stamens 

 to occur in distinct flowers from the pistils, so that the individual flowers 

 are imperfect, male or female : we have examples of this in the plants 

 of the Cucumber family, and also in most of our native forest-trees, such 

 as the Oak, Beech, Hazel, or even on entirely different plants, as in the 

 Willow and Poplar, &c. 



The carpels, the essential organs of a female flower, occur in two 

 conditions in Flowering or Seed-bearing plants ; and these two 

 conditions form the basis for the primary subdivision of this group. 



In by far the majority of flowers the carpels are folded up and 

 their edges united so as to form hollow cases, in the interior of 

 which the ovules are enclosed. In such instances the pistil is 

 divisible into regions, of which the lower hollow portion, called the 

 ovary, is the most important : very frequently a stalk-like process, 

 the style, is prolonged upward from its summit, terminating above 

 in a more or less thickened head, called the stigma, which marks 

 the position of an orifice leading down through the tubular or 

 spongy tissue of the style into the cavity of the ovary. In many 

 cases the stigma is seated immediately upon the top of the ovary, 

 without an intervening style (Poppy, Tulip). Plants bearing 

 their ovules in such closed ovaries are called Angiospermous, or 

 covered-seeded. 



In Pines, Firs, the Yew, Juniper, and in the exotic family of 

 the Cycads, the sexual organs occur in distinct flowers ; and these 

 flowers are not only devoid of proper floral envelopes, but are re- 

 duced respectively to single stamens and single carpels, mostly col- 

 lected into male and female cones. The anthers of the male cones 



