Clematis is a flowering plant (angiosperm). The genus Clematis
belongs to the family of plants Ranunculaceae (48 genera), in common with wild
plants such as buttercup and kingcup, and the garden plants anemone, delphinium,
paeony and hellebore. Clematis is classed as a woody plant as its stem becomes tough
and fibrous after two or three years; even so, there are a few exceptions such as the
herbaceous clematis. Clematis plants are mostly climbing, some clamber and a few
are herbaceous (the stem persisting for only one season). The plants are mostly
deciduous (lose leaves at the end of the growing season), but there are some
evergreen exceptions. The leaves usually are in opposite pairs. The climbing varieties
of clematis are not self clinging, but they twist for support by using a leaf stalk
(petiole) as a tendril to cling with.
Clematis have one unusual feature: the petals are aborted and the sepals take on
the characteristics of petals and are
termed tepals. In a related genus, Atragene, there is a ring of petaloid
staminodes (infertile organs) between the sepals and the stamens. For convenience,
atragenes are now included under the term Clematis. It is characteristic of clematis to
have numerous stamens and they are often a striking feature of the plant. The
flowers produce no nectar, only pollen. Insects are attracted by the bright tepals
and stamens and visit for the pollen. The clematis plant is monoecious (has male
and female flowers on the same plant) but there are exceptions; some of the New
Zealand clematis are dioecious (having male and female flowers on different
plants). The fruits of some clematis are so feathered as to be very conspicuous and
are sometimes grown for this feature alone.
The commonest clematis colors of flowers are dark blues, purples and mauves, but this range
is now being extended. We now have the clear white of, for instance, ‘Marie
Boisselot’; the beautiful
yellow of C. orientalis ‘Bill MacKenzie’; or the pink of ‘Comtesse de Bouchaud’;
the red of ‘Ernest Markham’ and ‘Niobe’; the clear blue of ‘Perle d’ Azur’; the
darker blue of ‘Lasurstern’. The stronger the light in which the clematis is grown,
the more intense the color. If there is little light, especially early in the season,
the paler clematis may show a green tinge. Too strong light, on the other hand, can
lead to fading. The stamens of many clematis are very conspicuous, often
colored, and dramatically improve the impact of the flower.
Most clematis flowers are single but a number of the cultivars are double, and a
few almost take on the character of a paeony. While most clematis tend to open
to a flat shape, there are many variations on this. There is the tiny star of blue-white
C. flammula, the single bell of C. alpina, the double bell of C. macropetala, the
tubular bloom of C. rehderiana, the tulip shape of C. texensis and the lanterns of
C. tangutica and C. orientalis.
In the species the blooms tend to be tiny but the plants make up for it by producing
blooms in large numbers. The hybrids, on the other hand, can produce flowers that
may be up to 25 cm (10 in) across. A well grown clematis can be very productive of
flowers. There may be as many as 500 flowers on a well established plant and in
the Jackmanii group this can rise to 1500. The Japanese, who specialize in growing
clematis in pots, expect to get up to 200 flowers in a pot plant. Amongst the
species, of course, the flowers are smaller but make up for this with a cascade of
blooms. Some of the blooming can be almost continuous through the summer months.
Clematis vary greatly in height from the 8 cm (3 in) of C. marmoraria, the
delightful alpine New Zealand clematis, to C. montana varieties which can soar
12m (40ft) up a tree. Tall, early species include C. armandii, C. montana, C.
chrysocoma, C. spooneri. Later, in the summer, comes C. campaniflora and later
still, in the autumn, C. viticella varieties, C. flammula and C. rehderiana.
The tall growing species are particularly valuable for covering an unsightly feature in the
garden or climbing a tree. The tall-growing large bloomers are good for
peeping in at a first floor window, or for reaching round a corner, or for stretching
over a wall. The short-growing cultivars can be equally useful. They can be grown
with the tall-growing varieties and hide the bare lower stems of the latter. They
are useful too in small patio areas or for growing over low walls or low shrubs.
A great joy is that so many clematis are perfumed, and some very strongly so.
Sadly, this is not true of the large-bloomed clematis: amongst these only
‘Fair Rosamond’ can claim any strong scent, and ‘Barbara Jackman’, ‘Duchess
of Edinburgh’ and ‘Sylvia Denny’ are faintly perfumed. The picture among the
species, however, is very different: starting from C. armandii in the early
spring, to C. rehderiana in the late autumn, there is a procession of sweetly scented clematis.
Some clematis are grown for their eye-catching seed heads. These are bordering
on the spectacular in many of the wild species. Particularly striking is C. vitalba
in the UK. The alpina and macropetala species are the first to display their seed
heads in the summer and are followed in late summer by the silky seed heads of
C. tangutica and C. orientalis, to be followed still later by the silver grey of C.flammula.
Some ‘clematarians’ have to contend with extremely low, unfavorable,
temperatures. In these conditions, there are ways to success. For instance, the local native
species, which are likely to be hardy, can be grown. Again, the species alpina and
macropetala are hardy to very low temperatures; C. fargesii and C. recta can
do well. Furthermore, the late-flowering species such as C. viticella,
c. x jouiniana, C. orientalis and C. tangutica can be grown, but cut down to the ground in late
autumn; if the roots are well protected they will survive the winter. The same
treatment can be given to some of the late-flowering cultivars. Some of the
cultivars have a good reputation in cold climates and these include ‘Victoria’,
‘Hagley Hybrid’, ‘Jackmanii’, ‘Perle d’ Azur’, ‘Niobe’, ‘Gipsy Queen’,
‘Comtesse de Bouchaud’, and ‘Ville de Lyon’. As a last resort, in extreme conditions, the
clematis can even be grown in containers and brought indoors in the winter.
What are the faults of clematis? Some would complain that in winter many
clematis look black and unsightly without leaves. In most cases, however, this
problem can be easily overcome by pruning late-flowering species and
cultivars in the autumn -a partial pruning -to be followed by a hard pruning in the
spring. In those varieties requiring light pruning, the bare stalks can be hidden by
planting shrubs in front of them. Some clematis are said to have bare bottoms
even in the flowering period. This can be dealt with by planting a short-stemmed
clematis alongside the long-stemmed clematis. Or again, it is possible to bring
down some of the high flowering trusses nearer the ground. The very vigorous montanas seem to be the most notable sufferers of bare stems in winter. Thus,
these should be planted where they are not seen from the house during this period.
Then, in the late spring, one can walk to a vantage point to enjoy their spectacular
Another complaint is the tendency of some of the more vigorous clematis to
tangle with one another, thus making a thick wad of bloom. This is really the
result of defective pruning which, if correctly done and with proper training,
will spread the clematis plant out so that the flowers can be seen to advantage.
Taking care of clematis
Conservatory and cut-flower clematis
Planting clematis in containers
Cultivation of clematis
Clematis in the garden
Pests and diseases