5M 
PINUS 
helping it to float in the air. In the ? , the cpls. themselves are very 
small, but the ovuliferous scales, which show at the outside of the 
cone, are very large, and each bears two ovules at its base, with the 
micropyles facing the axis. The ? cones take 2 to 3 years before the 
seeds are ripe. In May of the first year, the. first stage may be seen — 
young cones, about 1 cm. long, in the position of short shoots near 
the tip of the lengthening axis. Microscopic examination of these 
(see text-books) shows that the ovules are not ripe for fertilisation. 
In June (the time varies from year to year according to season) polli- 
nation takes place. The S cones shed their pollen in great quantities, 
so that in a pine forest the air is often full of it (if it rain, the pheno- 
menon of ‘showers of sulphur’ may occur), and the wind carries it 
about. At the same time the ovuliferous scales spread apart. If a 
grain fall between two of them it slips down to the micropyle of 
an ovule, where it becomes held by the sticky fluid then exuding. 
After a short time the ? cones close up again. The pollen grain is 
brought into contact with the nucellus by the drying up of the mucil- 
age; it forms a short pollen-tube, and then a resting period comes 
on. Next year in May or June the % cone has become a fat green 
body about 3 cm. long, with the ovules ready for fertilisation; the 
pollen- tubes now recommence growth and reach the ova. Then in 
the third year the cone is mature — a hard woody cone containing the 
seeds between the scales. Each seed contains an embryo with a 
w r horl of cotyledons, embedded in rich endosperm, and has a hard 
testa. To the end of this is attached a thin membranous wing, 
derived from the ovuliferous scale. In dry weather the cone opens 
and the seeds are blown away by the wind. In germination the 
seed is lifted up above the earth by the growing plant and the coty- 
ledons remain inside the testa till all the reserves are exhausted. It 
is noteworthy that they are green whilst in the seed, though in dark- 
ness — an exception to the rule that chlorophyll requires light for its 
formation. During the first year no short shoots are formed, and the 
seedling has green leaves borne directly on the main stem. 
The pines are amongst the most valuable of all plants and are 
cultivated on an enormous scale, chiefly for their timber, which is 
easily worked, and resinous products. The resin renders the timber 
very resistent to decay, &c. 
Some of the more important sp. will now be mentioned. 
I. PINASTER Endl. Visible part of fruit scale more or less 
pyramidal with central boss. 
§ 1. Pinea (short shoot with 2 or rarely 1 needles) : 20 sp. 
P. sylvestris L., the Scotch fir, the only British sp., occurs 
in Eur. to 68° N., in Asia to 66° N., and as far south as 
Spain and Italy (alpine). The wood (yellow deal) is largely 
used in the arts; turpentine is obtained by tapping the tree. 
The resin exudes and is distilled; the distillate is oil of 
