210 



ESSENTIAL ORGANS. THE PISTIL. 



especially at the period of fecundation, elongated tubes, ff, which in 

 part fill up the canal The name, conducting tissue, is given to that 

 found in the canal of the style, on account of the part which it plays 

 in conveying the influence of the pollen to the ovules, as will be ex- 

 plained under fertilization. 



433. The Stigma is a continuation of the cellular tissue in the centre 

 of the style, and it may be either terminal, when the canal opens at 

 the top only (figs. 373 s, 376, 1), or lateral, when the splitting of the 

 canal takes place on one side (fig. 377 s), or on both sides (fig. 378 s s). 

 The stigma sometimes extends along the whole length of the style. 

 In Orchidaceous plants, it is placed on a part of the column called the 

 gynizus (yt>), pistil, and Zga, I sit). It is composed of cellular tissue 

 more or less lax, and often having projecting cellules in the form of 



papilla? (fig. 376, 2), or of hairs (figs. 379, 3, 410 s), and at the 

 period of fertilization exuding a viscous fluid, which retains the grams 

 of pollen, and causes the protrusion of tubes. 



434. A pistil is xisually formed by more than one carpel. The 

 carpels may be arranged like leaves, either at the same or nearly the 

 same height in a verticil (figs. 380, 381), or at different heights in a 

 spiral cycle (fig. 306 c). When they remain separate and distinct, thus 

 showing at once the composition of the pistil, as in Caltha, Kanun- 

 culus, Hellebore, and Butomus (fig. 381), the term apocarpus (a., 

 separate, and Ketovos, fruit) is applied. Thus, hi Crassula rubens 

 (fig. 258), the pistil consists of five verticillate carpels, o, alternating 

 with the stamens, e ; and the same arrangement is seen hi Zanthoxylon 



Fig. 376. L Stigma, *, of Daphne Laureola, terminating the style, t, o, Summit of the 

 ovary. ?. A small portion of the surface of the stigma, much magnified to show its papillae. 



Fig. 377. Unilateral stigma, s, of Asimina triloba. t, Style. 



Fig. 378 Bilateral stigma, s s, of Plantago saxatilis. o, Ovary. , Style. 



Fig. 379. 1. Summit of the style, t, of Hibiscus palustris, dividing into five branches, which 

 are each terminated by a stigma, s. 2. One of these branches highly magnified. 3. Portion 

 of the surface of the stigma still more magnified to show its papillae, which are elongated like 

 hairs. 



