LESSON 18.] 



OPEN PISTILS. 



121 





321. The ovary, especially when compound, is often covered by 

 and united with the tube of the calyx, as has already been explained 

 (272). We describe this by saying either " ovary adherent," or 

 " calyx adherent," &c. Or we say " ovary inferior" when the tube 

 of the calyx is adherent throughout to 



the surface of the ovary, so that its 



lobes, and all the rest of the flower, 



appear to be borne on its summit, as 



in Fig. 215 and Fig. 216; or "half- 



inferior" as in the Purslane (Fig. 214), 



where the calyx is adherent part way up ; or " superior" where the 



calyx and the ovary are not combined, as in the Cherry (Fig. 213) 



and the like, that is, where these parts are free. The term " ovary 



superior," therefore, means just the same as " calyx inferior " ; and 



" ovary inferior," the same as " calyx superior." 



322. Open or Gymnospermous Pistil, This is what we have in the 



whole Pine family, the most peculiar, and yet the simplest, 

 of all pistils. While the ordinary simple pistil in the eye 

 of the botanist represents a leaf rolled together into a 

 closed pod (305), those of the Pine, Larch (Fig. 264), 

 Cedar, and Arbor- Vitse (Fig. 265, 



266) are plainly 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 staminate blossoms, falls di- 

 rectly upon the exposed ovules. Afterwards 



the scales close over each other until the 



seeds are ripe. Then they separate again, 



that the seeds may be shed. As their ovules and seeds are not 



enclosed in a pod, all such plants are said to be Gymnospermous, 



that is, naked-seeded. 



FIG. 262. Cross-section of the ovary of Hypericum graveolens. 263. Similar section of 

 the ripe pod of the same. 



FIG. 264. A pistil, that is, a scale of the cone, of a Larch, at the time of flowering ; 

 inside view, showing its pair of naked ovules. 



FIG. 265. Branchlet of the American Arbor- Vitae, considerably larger than in nature, 

 terminated by its pistillate flowers, each consisting of a single scale (an open pistil), together 

 forming a small cone. 



FIG. 266. One of the scales or pistils of tlie last, removed and more enlarged, the inside 

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



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