ENGELMANN—NORTH AM. SPECIES OF JUNCUS. 437 
GEOGRAPHICAL DISTRIBUTION. 
Of the fifty species above enumerated, thirty-three, or 
two-thirds, are peculiar to our country, and seventeen, or 
one-third, occur also in other parts of the world. Two of 
these seventeen (J. effusus and bufonius) are cosmopolitan 
species, which are found almost in all countries of our globe ; 
six (J. arcticus, trifidus, biglumis, triglunis, stygius, and 
castaneus) are alpine or arctic forms, which also inhabit 
appropriate localities in the old world; three (J. acutus, 
Balticus, and Gerardi) grow principally near salt water, 
and also occur in Europe, and the former, also, in Africa and 
South America; three others (J. filiformis, articulatus, and 
alpinus) make their home in the northern parts of the north- 
ern hemisphere; one (J. tenwis) is also found in middle 
America and western Europe; and two extend southward 
over our limits, J. compressus into Mexico, and J. procerus, 
if our plant is correctly referred, to Chili. 
The different forms of J. Balticus, nodosus, and Canaden- 
sis, grow in difterent regions. The eastern and northern J. 
Balticus is distinct from the form of the interior plains, 
and very much so from that of the Pacific coast; the Texan 
form of J. nodosus is very different from the northern one, 
and that of the western States and territories is quite unlike 
the others; J. Canadensis has a northern, an eastern, and 
a third form, which is more generally distributed, 
None of the eight southern species are found anywhere 
else, and of the nine Pacific species only the two above men- 
tioned extend beyond our territory to other parts of America, 
adding another proof of the well known fact, that of all our 
Floras that of the southern and that of the Pacific States are 
the most peculiar and exclusive ones. 
From their geographical distribution our species may be 
arranged thus: 
1. Over the whole country grow J. effusus, tenuis, bufont- 
us, and nodosus. Of these only the last one does not extend 
into other Floras. 
2. Over the whole country, with the exception of the 
western Plains and Mountains and the Pacific slope: J. 
marginatus and pallescens, both peculiarly North American. 
3. Over the whole country with the exception of the great 
interior valley and the Pacific region: J. pelocarpus and 
Canadensis ; both only found in North America. 
4, In the great interior valley from Michigan to the Rio 
Grande: J. brachycarpus, and, with more extensive limits, 
one of the forms of J. nodosus (the var. megacephalus ). 
5. Northward—J. jiliformis and the northern varieties of 
J. nodosus and Canadensis; north-eastward—J. articulatus, 
