Northwards chinooks become less frequent and the winter's cold increases, but the coming of spring is not much later, and the summer temperatures, with sunshine for twenty hours out of twenty-four in June, are almost the same as for hundreds of miles to the south, so that most kinds of grain and vegetables ripen far to the north in the Peace river valley.
A number of ova ripen simultaneously.
As in all poplars, the catkins expand in early spring, long before the leaves unfold; the ovaries bear four linear stigma lobes; the capsules ripen in May.
The damage may be only slight, or the entire boll may ripen prematurely and become dry and dead.
It is a straight-growing tree, with grey bark and whorls of horizontal branches giving a cylindro-conical outline; the leaves are short, rigid and glaucous; the cones, oblong and rather pointing upwards, grow only near the top of the tree, and ripen in the second autumn; the seeds are oily like those of P. Pinea, and are eaten both on the Alps and by the inhabitants of Siberia; a fine oil is expressed from them which is used both for food and in lamps, but, like that of the Italian pine, it soon turns rancid.
The process begins with the formation of brilliant granules (A, B); these increase, and the brilliant substance gradually balls together (C) and forms the spores (D), one in each segment, which soon acquire a membrane and ripen (E).
The cones do not ripen till the second year.
Axillary or terminal spikes; they have four stamens, which bear at the back four small herbaceous petal-like structures, and four free carpels, which ripen to form four small green fleshy fruits, each containing one seed within a hard inner coat;.
Do not ripen their fruit owing to imperfect fertilization, - is to be sought in this natural tendency to dioecism.
Cabbage, said to have been introduced by a detachment of Cromwellian soldiers, is also raised, and among fruits black and red currants ripen in sheltered situations.