* in the Seeds q/*Acanthace3e. 73 



Nelsonia tomentosa, Ebermaiera thyrsoidea, and Erythracanthus prostratus, 

 all belonging to Nees von Esen beck's tribe of Nelsonice, bear a striking resem- 

 blance in their seeds, which are very small, nearly globular, usually somewhat 

 tuberculated, and furnished with very minute hairs, closely appressed, sparingly 

 scattered over the surface, and wholly destitute of mucilage. In N. tomentosa 

 these hairs expand very slowly when wetted, and present the appearance of 

 short simple tubes, more or less incurved or uncinate at their extremities, and 

 frequently ending in a double hook. In Ebermaiera and Erythracanthus the 

 hairs appear to be similar, but owing to their extreme minuteness, and the 

 very slight action which water has upon them, I have not been able to satisfy 

 myself fully upon this point. 



Having now completed my account of those Acanthaceaj whose seeds I 

 have observed to be furnished with hairs, it only remains for me to mention 

 the species in which no such appendages have been met with, and to indicate 

 such peculiarities of structure as may seem to deserve particular notice, pre- 

 mising as a general remark, that the whole of them agree in being destitute of 

 mucilage. 



Acanthus mollis, Acanthus arboreus, Dilivaria ilicifolia. — The entire absence 

 of hairs on the seeds of these two genera is remarkable, when we consider their 

 close relationship to Acanthodium and Blepharis, in which these organs are 

 most highly developed. The structure of their testa is totally different, being 

 very thick, opake, and even woody, whilst in the two latter genera it is thin 

 and membranous. 



Crossandra infundibuliformis. — The seed, which is oval and slightly com- 

 pressed, is covered with numerous flat, scale-like, imbricated processes, which 

 give it some resemblance to a pine-cone ; the scales which proceed from the 

 sides of the seed are broad, thin, striated, dilated upwards, and irregularly 

 jagged at their extremities ; the marginal ones being usually longer and nar- 

 rower. 



Asystasia coromandeliana, A.macrocarpa, A.Neesiana, A.Kunthiana. — There 

 is much resemblance between the first three species in the size, form, and struc- 

 ture of their seeds, which are unusually large, reniform, much compressed, 

 swollen, and more or less crenated at the margin, with an uneven and furrowed 

 surface. . The testa is very thick and opake, and consists of an outer layer of 



VOL. XIX. L 



