44 



PITTONIA. 



woody, or even bony texture. Those last, as well as some of 

 the dehiscent kinds, are often furnished Avith curious wings 

 (Peltaria, Thijsanocarpus, etc.), or ears {Anas(aiica), stout 

 spines, horns and hooks {Ocfoceras, Noioceras, ParoUnin, 

 etc.). The instances in which carpal type of tlie Cruciferte 

 wanders away into unsiliquose mimicry of the fruits, and 

 even other organs of remote families are ratlier numerous. 

 The pods of Isatis iindoria strongly resemble the samaras 

 of the' ash tree ; those of Thyscmocarjyns and some others 

 the elm ; those of many species of Lcjndium are exteriorly 

 quite like the capsules in Veronica; those of Cakile and 

 Cramhe would be naturally mistaken for large flower-buds in 

 some other family of plants, if one did not know. The peri- 

 carps of TauscJwria, and more particidarly those of TJnjsano- 

 carpns conchulifer, are like small sea-shells.' 



The fruit of the order takes quite as surprising departures 

 from its type in another direction ; as when in Tetrapoma'' it 

 is found four-valved and wholly or partially four-celled ; or 

 in Tropidocarjmm; where it is not only one-celled, but opens 

 bivalvularly from the apex, thus exhibiting precisely a 

 certain capparideous type of pericarp. 



The organographic bond which, in the earlier years of this 

 family^s history, seemed to hold all the genera together in 

 despite of the wide carpological aberrations, was that of the 

 tetradynamous stamens. By this character, along with that 

 of the cruciform corolla, a tyro might recognise almost any of 

 the plants belonging to the order. The few exceptions to 

 teti-adynamy were not troublesome, so long as they were only 

 numerical, namely, by the stamens being reduced to four 

 through suppression of the two short ones, or even to two by 

 the absence of the four long ones. But in the light of many 

 discoveries made chiefly within the last fifty years, the excep- 

 tions are become troublesomely varied as well as here and 



' See Bull. Torr. Bot. Club, xiii 218 ; Pitt. i. 3L 



^ Turcz. Liiinrea, x. Lit. Ber. 104 ; Baillon Hist. iii. 18G. 



3 T. caffaridetim, Greene, Pitt. i. 217. 



