142 



ACADEMIC BOTANY. 



the Shepherd's-Purse (Pig. 200, C), whicli gets its name from its 

 resemblance to a Scotch shepherd's sporran. 



333. Dehiscence is Circumscissile, Porous, and Valvular. 



336. Circumscissile dehiscence gives us the first opening of the 

 loment (Fig. 197, BV It gives us the pyxidium : here the ovary may 



-he free (Fig. 197, D), with its upper part cut off as a lid ; or adherent 

 (Fig. 156). In the Monkey-pot the ovary is more than half adherent 

 to the calyx, forming the pot ; its upper part has an epigynous disk 

 which forms the lid.' Porous dehiscence is effected by pores or small 

 openings at the top of the boll, which otherwise remains closed. In 

 the Poppy (Fig. 197, E) the pores are just beneath the broad, sessile, 

 persistent stigma. In the Brazil-nut (Fig. 201, a) the large sessile 

 stigma falls off, leaving a pore, through which the germinating seeds 

 send their first roots ; but for this the boll would be indehiscent and 

 classed as a nut. 



337. Valvular dehiscence is always vertical ; it is the most com- 

 mon mode. It has four expressions : Locullcidal, Septicidal, Septif- 

 ragal, and Sutural. 



Fig. 204. — A, diagram of JPharbitU hitipida. B, boll of same, trans, sec. C, disaepi- 

 mente and seed. D, diagram of Heart's-ease ( Viola tricolor), £, boll of same. 



338. Loeulicidal (L. loeulus, cell ; coedo, I cut). Here each carpel 

 opens at the dorsal suture, thus cutting into the cell; as in the Nar- 

 cissus (Fig. 202), the Lily, the Olcra, and Cotton. 



339. Septicidal (L. septum, partition). Here the dissepiments sepa- 

 rate (are cut apart, as it were), leaving each carpel or cell closed. 

 Each cell then opens either by the dorsal suture, as in the Castor-Oil 

 Plant (Fig. 203, A), or by the ventral suture, as in the Foxglove 

 (Fig. 203, C). 



340. Septifragal [It. frango, I break). This is a modification either 

 of the loeulicidal or of the septicidal mode. Here the valves break 

 away from the partitions. Jussieu compares this mode to the rents 

 which sometimes occur in our garments ; the seam does not rip, but 

 the cloth tears away on each side of the seam. The Morning-Glories 

 (Fig. 204, A, B, C) show the septifragal modification of the septicidal 

 mode; the Violets (Fig. 204, D, E) show the septifragal modification 

 of the loeulicidal mode. 



341. Sutural (dehiscence by the sutures) is the common mode, and 

 usually occure at the ventral suture, as in the Pea (Fig. 5, e). 



