Cléthra arbórea, and C. arbórea variagàta, are both fine shrubs; the latter is preferable; leaves are oblong, accuminate, and serrated with a gold edge; flowers white, downy, in large branching racemose spikes, and sweet-scented; grows freely.
Cotoneásters. Two of this genus are deserving a situation in the Green-house, C. denticulàta, and C. microphylla; the last is a native of the mountainous districts of Nepaul, and may prove hardy; the flowers are white, small, and solitary, but in the fall it is covered with pretty red berries, and then looks beautiful; culture very easy; will grow in any situation.
Cròwea solígna, is amongst one of the finest and easiest cultivated plants of New South Wales. It flowers at the axils of the leaves, colour pink, with five petals, connected by entangled hairs; in flower from April to December, and frequently through the winter; foliage lanceolate, and a fine green. The plant grows neat, and requires an airy situation; drain the pots well.
Chorizèmas, about six species, foliage very like some varieties of the Holly; flowers small and papilionaceous; colour red and yellow; though small, they are very neat. C. nàna and C. ilicifòlia are amongst the best; if grown from seed, they will flower freely the second year; drain the pots well.
Cineràrias, Cape aster, about twelve belong to the Green-house. They are herbaceous, or half shrubby, soft wooded plants. C. speciòsa, C. amelloídes, (now called Agathæa cæléstus,) C. purpùrea, and C. lanàta, are among the finest; flowers blue or yellow; the latter is considered the handsomest of the genus. The exterior petals are bright purple, and the interior ones white, and with A. cæléstus, flowers most of the year; flowers syngenesious and star-like. The herbaceous species must be treated as previously mentioned for that kind of plants.
Cístus, or Rock rose. There are above thirty species, principally natives of Europe, consequently hardy there, and form a great ornament to their gardens, being very abundant and various in flower; but with us they will not stand the rigour of winter. We have no doubt, however, but, through time, some kinds may be grown that will withstand the greatest cold of the middle states; they are low shrubby plants of easy cultivation. C. ladaníferus, C. monspeliénsis, C. sálignus, C. popolifòlius, and C. undulàtus, are perhaps the best; the flowers are of short duration, frequently only for one day; but the quantity makes up this deficiency, being constantly in flower in May and June, and sometimes flower again in autumn. C. crèticus is most productive of the Gum laudanum, which is secreted about its leaves and branches. The flowers are generally five-petaled, and some of them large; centre full of stamens; the foundation of the natural order Cistinea.
Clématis, Virgin's Bower. There are only six of these belonging to this, all climbing plants. C. aristàta and C. brachiàta are the best; flowers in racemose clusters, pure white; foliage small; and natives of the Cape of Good Hope. The foliage of C. aristàta is cordate and blotched.
Cobæa scándens, the only species. It is a climber of very rapid growth, has been known to grow above two hundred feet in one summer; large bell-shaped flowers; when they are newly expanded, they are of a pale green colour, and change to dark purple; will grow in the garden during summer, bearing a continual profusion of flowers, but will not stand frost. When this plant becomes too large in the house, do not cut it close to the root, except there is a young shoot arising to carry off the superabundant sap, for the old wood will not push, which will soon cause a mortification.
The best method to adopt in such case is to turn back a shoot, and lay it in the ground to root, when it will become a young plant; which should always be done as soon as it appears unsightly. It does best to be planted in the ground, but will not give any satisfaction as to flowering in a pot. It will flower as an annual if sown in pots this month, and placed in a warm room or hot-bed, and planted into the garden about the end of May.
Coroníllas, a very few are fine species in the Green-house. C. glaúca is a celebrated plant amongst us, as a free and early flowering shrub. C. valentíana and C. viminális are equally so, flower from April to June, colour yellow; papilionaceous flowers in clusters; agree best with shade. In summer they ought to be kept behind a fence, or under a tree, as the sun would destroy them in a few weeks. Drain the pots well.