QUILLWORT. 
391 
gathered in the same place, and at the same time, the rhizoma 
is very small and inconspicuous ; in a third specimen the rhi- 
zoma is very broad and concave at the base. The size of the 
tuber may depend on the age and vigour of the plant ; its ana- 
logy with the rhizoma of ferns I think considerable : when a 
number of the outer or lower fronds have ripened and dropped 
off, then and not before it becomes exposed to view.” 
Mr. Sansom has given the two supposed species a minute and 
careful examination, and has favoured me with the following 
remarks. — “ In the diffuse variety the seeds are globular or 
nearly so, and the sutures in many cases very indistinct, while 
in the erect plant the seeds are angular, the angles appearing to 
be formed by the swelling of the edges of the sutures, and thus 
giving it an angular appearance. Again, the texture of the 
seed is different ; in the diffuse plant it has a slightly pellucid 
appearance, while, in the erect variety, they are of a firmer tex- 
ture, appearing quite white and horny.” Mr. Sansom, however, 
suggests, with great propriety, the probability of the seeds which 
he examined being in different stages of maturity ; those which 
I have examined do not exhibit the differences which he has 
pointed out. 
Professor Graham says, “ I have found the slender tufted 
form noticed by Mr. Wilson, growing among the stouter solitary 
kind, with broader, shorter, spreading leaves, which are sometimes 
even recurved. I have been in the habit of attributing the first 
appearance to depth of water, and to the plants being younger ; 
but I have not observed these appearances with sufficient atten- 
tion to be very positive about this.” 
Sir J. E. Smith attempts an explanation of the cause of these 
varieties which I cannot consider entitled to much respect : he 
says, “ The taller, more slender and brittle variety |3., observed 
by Dr. Richardson, may perhaps be caused by those sudden 
risings of the water so frequent in mountainous countries, which 
will account for all the peculiar characteristics of this variety.”* 
The solution of the problem appears to me to be this. When 
the seeds arrive at maturity, the leaf, in whose base the capsule 
* Eng. Flor. iv. 331. 
