ENGELMANN—NORTH AM. SPECIES OF JUNCUS. 431 
with such different length of tail that only the absence of 
any other diagnostic characters can induce us to consider 
them as belonging to one and the same species. Much less 
can generic distinction be based upon this character, as was 
done by Desvaux, who comprised in his genus Marsipposper- 
mum all Junci with tailed seeds. Even E. Meyer’s (in Synop- 
sis Juncorum, 1822, and in Ledebour’s Flora Rossica, 1853) 
separation of the species with tailless seeds as a second section 
is unnatural, as not only tail-seeded kinds are found in all the 
great groups, but also species with intermediate seeds exist, 
which it would be difficult enough to place properly. R. Brown 
(Prod. Nov. Holl, p. 258) settles the whole question in the 
following pithy sentence: Mee secernende sunt ee que 
seminibus gaudent scobiformibus, testa silicit, que in pluri- 
bus utrinque laxa, in hisce valde elongata. 
The size of the seed varies from 0.1 to 2.0 lines in length, 
it mostly ranges between 0.2 and 0.5 lines, and rarely reaches 
0.4 lines; the tailed seeds are usually larger than the others, 
averaging from 0.5 to 2.0 lines in length; even without the 
appendage, J. trifidus has the bodies of the seeds of 0.5, J. 
castaneus of 0.5-0.6, and J. stygius of 0.7-0.8 line in length. 
The delicate markings of the seeds are so various, and in 
the same species so constant, that it will be useful to dwell a 
little longer on them. Their surface appears never quite, 
and rarely nearly, smooth, when magnified fifty or sixty times. 
We can almost always discover longitudinal ribs, more or less 
close together, from 8 or 12 to 30 or 40 or more around the 
seed; as it is difficult to count the ribs all around these small 
bodies, and as an approximate designation is quite sufficient, 
only the number visible on one side may be counted. These 
ribs are very marked, sharply elevated, in J. marginatus (sem- 
ina costata), or they are reduced to more delicate lines in J. 
Canadensis and most tail-seeded species (semina multico- 
stata and striato-costata). These ribs or lines are usually 
united by very delicate transverse lines (lineole), when such 
seeds may be termed costato-lineolata, or by fewer, more 
prominent cross-bars, semina costato-reticulata. 
When the ribs are fewer and wider apart, and united by 
transverse ridges so as to form somewhat rectangular meshes, 
I call the seeds semina reticulata. The area of these meshes 
is sometimes quite smooth (J. militaris ), or crossed with very 
few transverse or longitudinal lines (J. scirpoides )—semina 
areis levibus reticulata—or it is distinctly marked by numer- 
ous delicate transverse lines, sometimes, also, with one or 
two perpendicular lines: semina areis lineolatis reticulata. 
In very few instances I find an irregular and indistinct retic- 
ulation: semina irregulariter sub-reticulata. 
A large number of Junci exhibit a very delicate but regular 
transverse reticulation without (in fully ripe seeds) very 
