Tender trees and shrubs that are natives of tropical America, Mexico and parts of the southern United States, and which belong to the Mallow family, Malvaceae. They are grown in tropical and subtropical countries as ornamentals and are sometimes cultivated in greenhouses. One, M. arboreus variety penduliflorus, is very freely planted in Florida and other parts of the far South, and is much admired for its bright crimson flowers, which are borne over a long period—in fall, winter and spring. The name is derived from Malva, a genus of plants, and viscosus, sticky, and refers to the sap.
Malvaviscus thrives without special care in a wide variety of soils and needs full sun for its best development. It is easily propagated by cuttings of leafy shoots planted in sand or vermiculite in a close propagating case in spring or summer. Seeds also afford a means of raising new plants. Pruning should receive attention in spring, after flowering. At that time old flowering shoots may be pruned back, and the crowded, unwanted ones removed.
When grown in greenhouses, these plants make handsome winter-flowering subjects in pots 7 in. in diameter or larger. They need a minimum winter temperature of 55-60 degrees; at lower temperatures they live but will not bloom well. They also need as much sunshine as possible.
In late spring, prune back old plants. Remove them from their pots, and, with a pointed stick, pick away as much old soil as can easily be removed from the outside of the root ball; now, repot them in well-drained containers in a rich, loamy soil. The soil should be packed quite firmly.
After potting, water should be applied in moderation until new roots take possession of the new soil; the tops should be syringed freely on all bright days. As the summer advances and the pots become filled with roots, more frequent watering will be necessary; at no time should the plants be allowed to suffer from dryness.
Repotting into larger receptacles (except in the case of specimens that are already in very large containers) will be necessary in June or July. Care must be taken at that time not to disturb the roots at all in the potting operation. After the potting is completed, the plants should be well watered with a fine spray and kept in the shade for a week or so.
During the warm summer months, pot-grown plants benefit from being plunged outdoors in a bed of ashes or sand in a sunny location, but they must be transferred to the greenhouse before the weather turns cold in the fall. From the time when their final pots are filled with roots, a weekly application of dilute complete liquid fertilizer will prove very advantageous.
Malvaviscus makes a fine specimen when trained in “standard” (tree-form) shape; shoots radiating from near a common center from the top of a 3-ft. or 4-ft. unbranched stem display the drooping flowers to perfection. Cuttings rooted in spring and grown on without pinching make very desirable decorative plants from November onwards.
The kind most commonly grown is M. arboreus variety penduliflorus (sometimes known in gardens as M. grandiflorus). It forms a spreading shrub 6-7 ft. tall with deep green leaves and flowers that measure 1-2 in. long. M. arboreus is native from Mexico to Peru and Brazil; its variety penduliflorus occurs naturally from Mexico to Colombia. Several more or less distinct varieties of M. arboreus are recognized by botanists, and it is likely that some of these are in cultivation.