NORTH AMERICAN SPECIES OF JUNCUS. 243 
sub-caudate variety from J. Canadensis, proving that differences in the surface or in the shape of the 
seed alone are not sufficient to establish specific distinction. 
What constitutes a Species. —The specific character lies not in any single organ of the [433] 
plant, however essential it may be; only sufficient and corresponding differences in a series of 
organs can authorize us to recognize specific distinction. But as such discrimination is of course left 
to individual judgment, different investigators will arrive at different conclusions. Some species, 
to be sure, vary very little, and will by every botanist be recognized as distinct from all others, and 
as indivisible; such are, e. g., J. filiformis, J. militaris, J. stygius, J. repens ; but other species exercise 
the botanists considerably, some forms being held distinct by some, while they are united by others. 
such are, among our species, especially J. pallescens, J. scirpoides, J. nodosus, and J. Canadensis, all 
belonging to the group Articulati. I have no doubt that some botanists, especially such as have not 
the means of comparing the bewildering quantity of transition forms now before me, will find my 
views in this respect too contracted, but careful investigation in the field will, I trust, bear me out. 
After these preliminary remarks I submit a list of our North American Junci and their prin- 
cipal varieties, as I understand them, followed by an account of their geographical distribution. 
Systematic Arrangement. 
GENUS JUNCUS, Linn. 
Sus-cenus I. JUNCUS. 
I, JUNCI GENUINI, caule aphyllo basi vaginis aphyllis seu rarius folia ipso cauli similia gerentibus stipato. 
Glomerulifiori. 
J. acutus, Linn., California, New Jersey (7). 
J. Remerianus, Scheele (J. maritimus, Auct. Am.), New Jersey to Texas. 
B. Singuliffori. 
Sages panicula fy u 
Robus tiores, sade ovatis seu a obovatis, 
‘TINILIAV 
agra 
Foliiferi 
3. J. compressus, H.B.K., Bias Mexico. 
2. Aphylili. 
* Hexandri. 
4. J. Breweri, n. ack -, California. . 
5. J. Balticus, ard. 
: CE coast of New England to the Baise 
montanus, western deserts and Rocky M 
ai naan J. Pacificus, Pacific coast. 
* Triandri. 
6. J. procerus, E. Mey. (?), California, 
7. J. effusus, Linn., over the Paso country.3 
B. aciliores, Sorin plerumque  peneages sepe viridulis, sepalis fructiferis sepe 
entibus, capsula subglobosa. 
‘SUNANNOD 
fi pans 
8. J. patens, E. Mey., California. 
9. J. filiformis, Linn., northward. 
hea 
10. J. Smithii, n. — , Pennsyl 
ll. J. setaceus, Rostk., Virginia Pe eases 
- Pauciflori, arg vix usquam composita. 
5 a erie Willd., Griednak 
Sub-sp. J. Sitchensis, northwestern coast. 
p. Cau 
*1OLLOUY 
1. Aphylli. 
13. J. Drummondii, E. Mey., Rocky Mountains and northwestward. 
. Foliiferi. 
14, J. Haliii, n. sp., Colorad 
15. J. Parryi, n. sp., Rocky ponte and mountains of California and Oregon. 
8 The triandrous J. Pylei, La Harpe, which is entirely unknown to me, seems to belong here, or near J. arcticus. 
