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.
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.