DAVALLIA — Hare's-foot Fern (Davall'ia). Greenhouse Ferns, most of which have fleshy rhizomes that creep over the surface of the soil: the rhizomes are covered with silvery white or brown hairy scales. They have finely divided fronds which arise directly from the horizontal rhizomes and vary in length from 6 in. to 6 ft. They are natives of northern Africa, tropical and sub tropical Asia, Malaya, Japan, northern India and Australia, and belong to the Polypody family, Polypodiaceae. Davallia was named in honor of Edmund Davall, a Swiss botanist.
They require a compost of equal parts of peat, loam and leaf mold; sand should be added to the compost and, in addition, a small quantity of crushed charcoal. The tropical kinds need a minimum temperature of 55 degrees; those suitable for a cool greenhouse need a minimum temperature of 45 degrees. Repotting is done in February for the hothouse kinds and in March for the coolhouse kinds. Shallow pans are preferred for those with creeping rhizomes. Once the plants are established repotting is not necessary every year; a little fresh soil worked in between the rhizomes will keep them growing vigorously for several years.
Ferns for Hanging Baskets. Some kinds, especially D. bullata, D. Griffithiana, and D. dissecta, are suitable for growing in hanging baskets. The rhizomes are pegged down into the basket on the surface of the compost. The soil is kept moist and the rhizomes creep down over the sides of the baskets and cover them with a mass of fronds. The rhizomes of D. bullata are trained into various shapes; those which are sold by florists will produce fronds when moistened and placed in a warm room or greenhouse.
During the growing season Davallias require an abundance of water, but very little is required from October to February or March; the soil must then be allowed to become quite dry before it is moistened.
Propagation is by division of the rhizome or rootstock at potting time. The portions of rootstock are pegged down on the surface of the soil until sufficient roots have formed; they are then potted. Spores may also be sown during spring and summer. They are sprinkled on the surface of finely sifted compost, the pots being placed in a saucer of water and covered with glass. The little Ferns are afterwards pricked out, one inch apart, in shallow pans, kept in a closed propagating case and eventually potted separately in 3-in. pots.
The Chief Kinds. For the warm greenhouse: D. fejeensis, 11/2 ft.; D. alpina, 6 in.; D. dissecta, 6 in.; D. elegans, 2 ft.; D. heterophylla, 6 in.; D. denticulata, 18 in. For the cool greenhouse and as house plants: D. bullata (Squirrel's-foot Fern), 8 in.; D. canariensis (Hare's-foot Fern), 18 in.; and D. Mariesii, 6 in.
DAVIDIA—Dove Tree (David'ia). This is one of the most interesting of the leaf-losing new trees introduced from central and western China during the present century. In a state of nature it grows 60-70 ft. high, with a widespreading head, and it promises to reach a large size in favorable parts of North America, where there are already trees between 40 and 50 ft. high which flower and seed freely. Davidia is placed by some botanists in the Dogwood family, Cornaceae; other botanists place it in the Nyssa family, Nyssaceae. The name Davidia was given in honor of the French missionary, Armand David, who collected many botanical specimens in China between 1862 and 1873.
There is only one species, D. involucrata, but because of small differences noticeable in some trees two other names have been applied, D. Vilmoriniana and D. laeta. These are now usually accepted as varieties of D. involucrata. Vilmoriniana is the best form to plant, for it appears to grow more rapidly than the typical D. involucrata. It differs from D. involucrata in that the leaves are smooth and not covered with feltlike hairs beneath.
Although dried specimens of Davidia have been available since 1869, seeds were not received in Europe until 1897. These were sent to France, and of them one germinated in 1899, that being the form now called D. Vilmoriniana. About 1900 the late Dr. E. H. Wilson succeeded in sending to Messrs. Veitch in England a large number of seeds from which all three forms were raised.
A Remarkable Hardy Tree. Davidia is distinguished among hardy trees by its heart-shaped, long-stalked leaves, and by its globelike heads of small flowers being attended by two large, white, leaflike bracts. The largest bract is 6 in. long and half as wide, the other about two thirds that size. A tree in full flower appears as if covered with giant butterflies.
Raising Seedlings. Fertile seeds form a ready means of propagation. The outer pulp should be removed and the seeds sown in a sandy soil in a greenhouse or frame as soon as ripe. Germination should then take place in a few weeks. If, however, the seeds are allowed to dry before sowing they may not germinate for a year or more. Seedlings should be kept in a frame until danger of frost is past, and then be planted in a nursery border. When about three years old they should be large enough for their permanent positions. Cuttings of half-ripe side shoots taken in late summer can be rooted in a close frame.
Choose a sunny place with a background of dark-leaved trees for preference, and plant in deeply prepared soil, well-drained loam being ideal. The flowering time is late May and early June.
This tree is hardy in sheltered places in the vicinity of New York City and in southern New England. Young specimens are more tender than older trees and should receive winter protection in the North.