14 REPORT ON THE BOTANY OF 
dently remain active for several years. They bear their spore 
cases on the end of veins on the edges of the fronds. Inno 
case have I ever seen a frond, which seemed recently unfolded, 
develop its spore vessels. A season of repose, of longer or 
shorter duration, occurs after its development, before it puts 
forth its little cups, from the bottom of which the bristle grows, 
and at the base of which the sforangza develop and cluster. 
But what seemed still more curious to me is the fact that the 
crops of sforangia are not all formed and ripened at once; but 
they are successively developed at the base of the lengthening 
bristle. I have seen these bristles more than half an inch long, 
and still beset at the base with ripening sforangia, the: scars 
left by those long since fallen being still visible all along the 
bristle. I think the life of a fertile frond may be for as long as 
four or five years. It may not be out of place to add, that the 
fronds were generally well filled with spore vessels. It is prob- 
ably due to the fact that the numerous flocks of sheep which 
find protection under the overhanging cliffs during winter, and 
feed upon this fern, that its extinction seems so near at hand. 
There were hundreds of situations where it might flourish as 
well as where it was found, but where it is not found to grow; 
and those places where it was found were inaccessible to the 
sheep, either by being above their reach or too far under the 
rock. I had often to crawl or draw myself in to where it cov- 
ered the under surface of the overhanging rock, where there 
was barely room for my head and shoulders. 
ECONOMICAL NOTES. 
Turning to the more practical side of my work, I can say 
that the quantity of valuable timber-trees seems practically 
inexhaustible. 
Soft-wood.—The tulip tree, in the west commonly called pop- 
lar (Leriodendrvon tulipifera), is abundant along the tributaries 
of Green river. The trees are of large size, and make good 
lumber. Those which grew nearest the river and its principal 
tributaries have been mostly floated down the river; but in the 
country back there is still much of this valuable timber. 
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