The Alder
Of the three species of alder indigenous to Europe, namely Alnus incana, A. cordata and A. glutinosa, only the last named succeeded in establishing itself in the British Isles after the retreat of the ice-field; though the other two grow readily enough when planted in this country.
"Alnus, the alder," wrote John Evelyn, "is of all other the most faithful lover of waterie and boggie places, and those most despis'd weeping parts or water-galls of forests." It has never been a popular tree, either with foresters, poets, or landscape gardeners, yet it has the merit of clothing ground which will not satisfy the wants of any other lofty growth, thriving in swamps too sour even for the willow. "Where do you put your brown tree?" is said to have been asked by one artist of the Georgian era of another; and the rounded outline and sombre foliage of a mature alder must have served many of the old school of landscape painters in their conventional compositions.
The alder neither contributes tender verdure to the gaiety of spring nor brilliant tints to the splendour of autumn; dull rifle green is the livery donned in April, remaining unchanged till the frosts of late October. Nor does this melancholy tree gladden the waterside with any brightness of blossom; the male and female catkins, appearing before the leaves, are dull, brownish yellow; beautiful objects under a lens, but contributing little to cheer the wayfarer, save as being sure harbingers of summer days. These flowers are followed by cones, which are green at first, but, turning black when ripe, only serve to deepen the gloom. Nevertheless, an alder copse in February and early March has a quiet beauty all its own. The smooth twigs are glazed with a waxy secretion and the swelling buds are plum-coloured, which the level sun-rays light up into a charming purplish bloom. Many a time when in pursuit of spring salmon I have enjoyed the sight of a bevy of old blackcocks busy among the branches of the alders, whereof the buds and catkins provide them with provender during the hungriest months of the year.
There are about five-and-twenty known species of alder, all bearing a considerable family likeness, and none exceeding in stature our only native species, Alnus glutinosa. Of this, many specimens might be mentioned between 70 and 90 feet high, though it is often difficult or impossible to obtain right measurement owing to the trees growing beside rivers or lakes. The most remarkable alder wood known to me is at Kilmacurragh, in County Wicklow. In the old spacious days the ground it occupies was a deer park. The trees are ancient, but not very lofty, from 50 to 60 feet high; but many of them have clean boles up to 30 or 40 feet and girth from 8 to 10 feet. One of them had a girth of 11 feet 4 inches in 1906. In the swampier parts of the wood, some of the trees have got bowed; their trunks present a curious appearance from being densely covered with pennyroyal (Cotyledon umbilicus). There can be little doubt that this grove is a fragment of the primæval Irish forest.
There are some very fine alders beside the Gade in Cassiobury Park, Herts, one of which Dr. Henry made out to be 85 feet high, with a girth of 11 feet 6 inches; but these dimensions were exceeded by an alder 90 feet high with a girth of 11 feet 4 inches at Betchworth Park, Surrey, and by one at Enville Park, Stourbridge, 87 feet high, with a girth of 8 feet 2 inches.
In Scotland the tallest measured by him was at Scone—66 feet high by 6 feet 3 inches in girth; but no doubt there are bigger alders than that north of the Tweed, though it might not be possible to match a shapely tree measured in 1904 at Churchill, Co. Armagh, which stood 94 feet high, girthing 6 feet 4 inches, and having a clean bole of 60 feet.
The aforesaid tree at Scone is of the cut-leaved variety, a sport which, originating in France, and being planted in De la Berlière's garden near Saint-Germain, says Loudon, became the parent of all that are now to be found. It is certainly more ornamental than the common form, the leaves being divided half-way to the midrib into three to six segments on each side.