CHAPTER XI. — THE PISTILS, OR GYX.ECIUM. 



8l 



Practical Exercises. 



Examine the stamens of the freshly opened flowers of the following plants : 

 The Pumpkin, the common Mallow, the Tiger Lily, the Cherry, the Musk 

 Plant, and the wild Cucumber, and ascertain in each case ( I ) what parts are 

 present ; (2) whether the stamens are distinct or whether they are united to each 

 other or to other organs ; (3) whether they are hypogynous, perigynous, or 

 epigynous ; (4) whether the position of the anthers is extrose, introse or indif- 

 ferent ; (5)whether the anthers are one-celled, two-celled or four-celled ; (6) the 

 character of the connective ; (7) whether the anthers are innate, adnate or 

 versatile ; (8) whether their dehiscence is longitudinal, transverse, valvular or 

 porous ; (9) the shape and character of the filaments ; (10) the shape and mark- 

 ings of the pollen grains. In order to study the pollen grains, seize by means 

 of a delicate pair of forceps, a stamen whose anther is just dehiscing, tap the 

 latter gently on the surface of a clean sheet of white paper, and then examine 

 carefully the adhering grains by means of a good lens. The pollen grains of 

 many plants are so minute that they cannot be satisfactorily studied in this way ; 

 the student had better, therefore, if possible, use for the purpose a compound 

 microscope. 



CHAPTER XI.— THE PISTILS, OR GYN.ECIUM. 



The pistil is the female organ of reproduction of the flow- 

 ering plant. In the Pine and related plants, it consists of 

 an open leaf or scale, which bears but does not inclose the 



Fig. 255. Fig. 256. Fig. 257. Fig. 258. 



Fig. 255. — A leaf folded so as to illustrate the structure of a simple pistil or carpellary 

 leaf. 



Fig. 256. — A simple pistil cut transversely to show the cavity of the ovary and the 

 ovules, a is the stigma and 6 the style. 



Fig 257. — Follicle of Caltha, opened out to show its resemblance to a leaf. 



Fig 258. — Pea-pod, laid open to show the placenta, corresponding to the infolded 

 leaf-margins, and bearing a double row of ovules. 



