LESSON 18.] 



OPEN PISTILS. 



121 



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

 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. 2G4), 

 Cedar, and Arbor- Vit£B (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 ai"e not 

 enclosed in a pod, all such plants are said to be Gi/mnospermous, 



that is, naked-seeded. 



^ /' 



FIG. SC3. Cross-section of the ovary of Hypericum graveolons. S53. Similar section of 

 tile ripe pod of tlio same. 



FIG. 2c4. A pistil, tliat is, a scale of the cone, of a Larcli, at the time of flowering j 

 InsiiJo vie\v, showing its pair of nalced ovules. 



FIG. 2Co. Branchlet of the American Arbor- Vitie, considerably larger than in nature, 

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

 forming a small cone. 



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

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



11 



