SECTION 10. J 



PISTILS. 



log 



tiguous margins of two pistQ-leaves grown together. There is every grada- 

 tion between tbis and the three-celled ovary with the plaoentse in the axis, 

 even in the same genus, sometimes even in different stages in the same 

 pistil (Fig. 335, 836). 



§ 2. GYMNOSPERMOUS GYNCECIUM. 



313. The ordinary pistil has a closed ovary, and accordingly the pollen 

 can act upon the contained ovules only indirectly, through the stigma. 

 This is expressed in a term of Greelc derivation, viz. ; — 



Angiospermous, meaning that the seeds are borne in a sac or closed 

 vessel. The counterpart term is 



Gymnospermous, meaning naked-seeded. This kind of pistil, or gynoe- 

 cium, the simplest of all, yet the most peculiar, characterizes the Pine 

 family and its relatives. 



314. While the ordinary simple pistil is conceived by the botanist to 

 be a leaf rolled together into a closed pod (306), those of the 

 Pine, Larch (Pig. 337), Cedar, and Arbor- Vit^ (Fig. 338, 

 339) are open leaves, in the form of scales, each bearing two 

 or more ovules on the inner face, next the base. At the time 

 of blossoming, these pistil-leaves of the young cone diverge, 



and the pollen, so abundantly shed from the stam- 

 inate blossoms, falls directly upon the exposed/ 

 ovules. Afterward the scales close over each' 

 other until the seeds are ripe. Then they sepa- 

 rate that the seeds may be shed. As the pollen 

 acts directly on the ovules, such pistil (or organ 

 acting as pistil) has no stigma. 



315. In the Yew, and in Torreya and Gingko, 

 the gynoBcium is reduced to extremest simplicity, 

 that is, to a naked ovule, without any visible 

 carpel. 



316. In Cycas the large naked ovules are borne 

 on the margins or lobes of an obvious open leaf. All Gymnospeemous 

 plants have other peculiarities, also distinguishing them, as a class, from 

 Angiospebmous plants. 



Fio. 337. A pistil, that is, a scale of the cone, of a Larch, at the time of flower- 

 ing; inside view, showing its pair of naked ovules. 



Pio. 338. Branohlet of the American Arbor-Vitse, considerably larger than in 

 nature, terminated by its pistillate flowers, each consisting of a single scale (an 

 open pistil), together forming a small cone. 



Flo. 339. One of the scales or carpels of the last, removed and more enlarged, 

 the inside exposed to view, showing a pair of ovules on its base. 



