CHAPTER IX
TREES AND SHRUBS WITH BEAUTIFUL CATKINS
When thinking of trees and shrubs in early spring we must remember those with beautiful catkins. Of the earliest flowering hardy trees and shrubs the majority are those with flowers borne in catkins. Their appearance is one of the first evidences of the approach of spring. It is to the catkin-bearing group that the Poplars, Willows, Birches, and Alders belong. These catkins are pendulous, cylindrical, and often slender inflorescences, carrying flowers of one sex only, which spring from the axils of scaly bracts. Being mainly dependent upon the wind for their fertilisation, they have none of the varied or bright colours that are characteristic of flowers fertilised by insect agency. Often, indeed, sepals and petals are entirely absent. Still, many of these catkin-bearers possess a charm and beauty of their own, which, taken with the early, often inclement, season when they appear, make the best of them indispensable in gardens where early spring effects are desired. As a rule it is the male or pollen-bearing catkins that are most ornamental. They are longer and more graceful than the seed-bearing ones.
Poplars
First among Poplars to bear its flowers, and almost before winter is past, is the Aspen (Populus tremula). This and its weeping variety bear their catkins in February, but closely following it, and perhaps more ornamental, is the American Aspen (P. tremuloides). This species flowers early in March near London in mild seasons, but later further north, and when kept back by severe weather. The pendulous variety of P. tremuloides—known commonly as Parasol de St. Julien—is, at the flowering time, probably the most beautiful and striking of all catkin-bearing trees. This and also the type produce long, slender catkins that sway gently in the softest winds. The weeping variety, which has branches that weep naturally low, looks well by itself on a lawn. In all these Poplars the male catkins are three inches to four inches long, chiefly grey-brown in colour; the scale-like bracts, however, are suffused with a reddish shade. The weeping varieties of these two Aspens are frequently grafted on the White Poplar, which is not a suitable stock. The species to which the varieties severally belong should be used for the purpose. It would be even better if they could be got on their own roots by means of layers or cuttings, and trained up to the required height before allowing the weeping habit to develop.
There are other Poplars that bear their catkins freely, such as P. alba, nigra, and balsamifera, but being of loftier habit they do not show to the same advantage as those of the Aspen group.
Hazels
Between the middle and the end of February the flowers on the catkins of the various species of Corylus begin to expand. Early as that date is, the catkins have, nevertheless, been in evidence since the previous autumn; they were, in fact, formed before the nuts fell. Being comparatively low and shrubby the different varieties of the Hazel (Corylus Avellana) show their catkins to best advantage, and there are few among the catkin-bearers more charming. It is not often that any but the coloured-leaved varieties find a place in the garden proper, but either in the orchard or in the woodland the soft yellow of the Hazel catkins is one of the most pleasing notes of earliest spring. The Tree Hazel (Corylus Colurna), a fine and interesting tree, growing thirty feet or more high, also bears its catkins in February.