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.
WILLOWS
Of the almost innumerable species and varieties of _Salix_, it is only a
few that need be mentioned here for their beauty when in flower. So far
as I have been able to judge, the most ornamental of the Willows in
catkin time is _Salix smithiana_, known also as _S. mollissima_. This
tree flowers about mid-March, producing its shortish, thick male catkins
in very great abundance; the numerous exposed anthers give a soft but
glowing yellow tone to the tree, and entitle it to rank as one of the
most ornamental of early-flowering trees. The pendulous variety of
_Salix Capraea_ is known as the Kilmarnock Willow. Although of weeping
habit it is somewhat stiff in character; but towards the end of March
and later it is exceedingly pretty loaded with its grey catkins. The
flowers of the typical _S. Capraea_ (the Goat Willow) are commonly known
in many country places as Palm, and are used for decorating churches on
Palm Sunday. The slender, coloured twigs of the Purple Willow (_Salix
purpurea_) bear red or purplish-tinted catkins in early April. _Salix
stipularis_ may also be mentioned for its beauty when in flower.
ALDERS
With the exception of a few species, such as _Alnus nitida_ and _A.
maritima_, which flower in September and October, all the Alders develop
their blossoms in February and March. The common Alder (_A. glutinosa_)
and its varieties are perhaps as ornamental as any at that time. Like
the Willows, they look best and grow best in association with water. In
such a position an Alder at that time, leafless, but laden with its
slender, greenish-yellow catkins, is a beautiful object, and
characteristic, too, of our English landscape. Other species possessing
a similar quiet beauty are _Alnus incana_, _A. viridis_, _A. oregona_,
and especially _A. cordifolia_ with its green and yellow catkins.
JAPANESE WALNUTS
_Juglans sieboldiana_ and its close allies, _J. mandschurica_ and _J.
cordiformis_, do not flower till May, but bear at that time very
remarkable male catkins. I have measured them over one foot long, and
hanging as they do in goodly number from the branches, perfectly
straight and cylindrical, they have a very striking appearance, although
green. All three species are alike in their catkins, but differ in the
shape of the nuts. They are noteworthy, too, for the imposing character
of their foliage. The leaves are pinnate, and on young trees grown in
good soil are frequently three feet long. They certainly deserve the
notice of planters.
GARRYA ELLIPTICA
From all the catkin-bearers hitherto mentioned, this differs in being
evergreen. It is also far removed from them in relationship, and is
closely allied to the Cornels. At the same time the catkins in external
characteristics are very similar. Not only the catkins but the plants
themselves are unisexual, and, as is usual with the catkin-bearers, it
is the male that is most ornamental. These catkins are from four inches
to eight inches long, and I have heard of (but not seen) them as much as
one foot in length. The time at which the flowers expand depends, as
with all the early catkin-bearers, on the mildness of the season. This
year on a wall the catkins have been in beauty ever since the first week
of January. They are very attractive in their grace and quiet beauty.
Chiefly of soft grey and green colours, the bracts are, however,
suffused with a warmer reddish tint. In the neighbourhood of London
Garrya elliptica is quite hardy in ordinarily sheltered positions, but
does not flower so freely as against a south wall. As it is of
Californian origin this is not surprising. This shrub resents
disturbance at the root, and in transplanting great care is necessary.
There are other species of Garrya in cultivation, but they are more
suitable to the south-western counties than to the average climate of
Britain.
To the catkin-bearing family belong several other well-known trees, such
as the Birches, Hornbeams, and Sweet Chestnut; but flowering later in
the year their beauty is apt to pass without notice in the great flush
of bloom that comes in with April. The beautifully fragrant Sweet Gale
must not be passed without mention. Its reddish brown catkins are formed
before autumn, and expand on the still leafless twigs in spring.