173] ENGELMANN— REVISION OF THE GENUS PINUS, ETC. 13 
peculiarity of some species to retain their seeds in temporarily 
or permanently closed cones, when they are called serotinous. 
Such are southern forms of P. rigida (var. serotina) and P. inops 
(var. clausa), rarely P. Teda ; in some Californian (P. insignis, 
tuberculata,muricata) and Mexican species (P. patula, Teocote 
and Gregg?) this is still more conspicuous. The seeds of such 
serotinous cones seem to retain their germinating power for many 
years longer than loose pine seeds, which are known soon to lose 
their vitality.* - 
The sEEDs are obovate, or often more or less Sail ccite trian- 
gular, rarely (in P. Sedénéana and Gerardiana) nearly cylin- 
drical, generally somewhat compressed, 2 to 12 lines in length, 
smooth or often on the lower surface ridged or slightly tubercu- 
lated, always destitute of balsam vesicles, pale gray or yellow- 
ish, or spotted, or brown, and often black. A wing is always 
present, and is generally several times longer than the seed; in 
some large-seeded species (P. flexilis, Cembra, edulis and the 
other nut-pines, and Pézea) it is reduced to a narrow rim, which 
is apt to remain attached to the scale when the seed is liberated ; 
in P. parviflora, Bungeana, Gerardiana, Torreyana, and 
Sabiniana, itis more conspicuous, but shorter than the seed 
itself; in P. Coulterd it is about as long as the seed, and in P. 
Lambertiana longer. The size of the seed and the proportion 
of the wing to it has been considered to furnish valuable sec- 
tional characters, but it proves to be only of specific importance. 
The wing is always more or less oblique and widest in some 
species upwards, in others near the base. The base of the wing 
forms a rim which surrounds the seed, leaving its under side free 
and with its edge covering part of, or rarely the greater part (P. 
£lliottiz) or the entire upper side (only seen in P. Bankstana). 
Generally the wing and its rim is completely separable from the 
mature seed, but in a few species (P. Strodus and allies) it ad- 
heres to it closely, and is at last broken off irregularly. 
The coTyLEpons, 4 or 5 to 15 or 18 in number, are mostly 
several times shorter than the caulicle, usually not longer than its 
eeds from closed cones of P. contorta, two to eight years old when I collected them 
in pa a and then kept four Spee in a hot garret, germinated freely with Prof. Sargent 
of the Arnold Arboretum, Mas 
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