Colouration can be found on orchids, in particular among the tall-growing, two-leaved Cattleya species known as the bifoliate cattleyas. Purple shows up clearly on new growth, but is gradually lost. It may appear on the leaf’s upper surface and on the new sheaths protecting the growing pseudobulb. Odontoglossum grande covers the undersides of its leaves with delicate brown flecking, and many other examples may be found.
There are two distinct types of Paphiopedilum. These are the plain, or green-leaved, varieties, and the mottled-leaved varieties. The latter exhibit a tremendous variation between species and into the hybrids, where further intermediate patterns are formed.
An interesting fact about these plants concerns their leaf tips. Each species is of a different shape, the ends of the leaves having a ‘chewed’ appearance. This is a natural development and all monopodial leaf tips are serrated to a greater or lesser degree. A skilled orchid grower can identify one species from another merely by its leaf tips. Vanda tricolor have very pronounced characteristic. The jagged appearance shows clearly the uneven ending of the foliage.
Phalacnopsis are monopodial, growing continually from the centre. Being bulbless, the leaves are succulent, broad and flat. Some species can have leaves a mere i in (2.5 cm) in length, such as P. lobbii, whereas the largest of the species, P. gigantea, produces leaves 12 in (30 cm) wide. The plants grow in deep shade and the leaves are extremely sensitive to light, water and extremes in temperature. Although warm-growing (a minimum temperature of i 8 C, 65 F, suits them) the wide leaves will easily burn if exposed to direct sunlight.
Several non-related orchids have evolved with similar foliage, the short leaves close to the stem being a successful development when coping with harsh conditions. Lockhartia oerstedii is a species from Mexico, and this growth habit can also be found in dicheas from Honduras and the monopodial Angraecum distichum from East Africa, among others.
The Lockhartia stem will continue to extend for several years, flowering as it does so, until maturity is reached. The new growths do not wait for maturity of the previous stem but start growing each spring. The result is a considerably large plant within a few years, with stems up to a yard or metre high. At this stage they will form semi-pendent plants, ideal for growing naturally on a tree branch. It is an evergreen which will lose a few leaves each year from the base of the oldest stems. The delicate, plaited appearance hides a strong interior, and the plant can cope easily with adverse conditions. In cultivation, this type of foliage can be regularly sprayed with little risk. Such plants do well mounted on bark.