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169] ENGELMANN—REVISION OF THE GENUS PINUS, ETC. 9 
aster) or lacerate (P. Laméertiana) crest, or it terminates in a 
knob or a few teeth (in most S¢rodz and a few Pinasters such as 
P. Balfouriana and sylvestris). 
The POLLEN has the well known bilobed form, consisting of 
an elliptic central portion, which emits the pollen tubes, and two 
lateral sacs which are said to contain air. The longer diameter 
measures 0.025 to 0.045 lines, mostly between 0.030 and 0.040 
lines, while the pollen grains of Aédzes and Picea are much 
larger and in many instances twice as large, viz. 0.045 to 0.070 
lines long. Thus by the pollen alone Pénus can generally be 
distinguished from those allied genera. The different species of 
pines are pretty constant in the size of their pollen. 
Without going into minute detail, I will only state that I find 
pollen grains of 
0.025-0.030 lines in P. edulis and P. Banksiana ; 
0.030-0.035 ‘* in P. Balfouriana, peer ees grrr fe resinosa, 
Chihuahuana, Laricto, inops, contor 
0.035-0.040 “ in P. Strobus, excelsa, Pinea, rigida, T sion mitts; 
0.040-0.045 ‘* in P. Lambertiana, flexilis, cue terumea, Pinaster 
ponderosa, Sabiniana, Elliot 
The property of the pine-pollen to float for a long time in the 
air, and to be carried by storms to very distant localities, is well 
known. I have found in streets of St. Louis after a rainstorm 
from the south, in March when no pines north of Louisiana were 
in bloom, pine-pollen which must have come from the forests of 
P. australis on Red river, a distance of about 6} degrees of lati- 
tude or 400 miles in a direct line. 
The FEMALE FLOWER consists, as in all Adée¢inea@, of a car- 
pellary scale in the axil of a smaller, concealed, bract, bearing two 
pendulous ovules on the lower part of the upper side. A number 
of such scales in the axils of their supporting bracts, and spirally 
arranged, form the female ament. The question of the nature 
of the scales, and of the ovules they bear, is not to be discussed 
here, but it may be stated that the best lights force the view on 
us that the carpellary scale consists morphologically of two leaf- 
organs, lateral to an undeveloped axis and united at their poste- 
rior edges (those turned towards the axis of the ament), and thus 
bearing their naked ovules on their morphologically outer but 
now reversed and apparently upper side. 
