(named for James Dickson, an English botanist, 1738-1822). Cyatheaceae. Tree ferns of greenhouses.

Plants with a distinctly 2-valved inferior indusium, the outer valve formed by the apex of the leaf - segment -A small genus, mostly of the southern hemisphere. For D. pilosiuscula, D. punctilobula and D. Smithii, see Dennstaedtia. For D. Schiedei and D. regalis, see Cibotium. These are only two of several confusions of species which have been called Dicksonia, but really belong in other genera. Modern fern students are now reaching the conclusion that Dicksonia is not only very distinct from the genus Cyathea and its relatives, but belongs in a distinct family.

Dicksonias are amongst the most important tree ferns, both for their beauty and because of their relative hardiness. In their native countries some of them are occasionally weighted with snow, and D. antarctica has to endure frosts. They can be grown in coolhouses, and should be tried southward outdoors in sheltered places. Their trunks are more fibrous than those of most tree ferns, and hence more retentive of moisture, so that they need less care. A good trunk produces thirty to forty fronds a year, and retains them until the next set is matured, unless the trees suffer for moisture in winter. Although they rest in winter, the fronds soon shrivel up if the trunks are allowed to get too dry. Dicksonias should have their trunks thoroughly watered twice a day during the growing season. These waterings should be gradually decreased until winter, when the trunks should be kept merely moist all the time. Only in the hottest summer days is slight shade needed. It is a pity to grow tree ferns in pots, but if this must be done several principles should be observed. The lapse of a single day's watering will often cause serious damage. As a rule, the pots should be of the smallest size consistent with the size of the trunk. Three or 4 inches of soil all around the trunks are enough.

The above points are taken from Schneider's "Book of Choice Ferns;" see also the discussion of tree ferns, under Ferns, Vol. III.

Antarctica

Labill. leaf - stalks short, the scales dense, dark purplish brown; leaves 5-6 ft. long, the middle pinnae 12-18 in. long; segments oblong, the sterile incised. Austral, and Tasmania. G.C. III. 9:81. - Trunk sometimes 30-35 ft. high. A very useful decorative plant.

Squarrasa

Swartz. leaf - stalks short, the scales hairlike, light colored: leaves 3-4 ft. long, the pinnae 9-15 in. long; segments lanceolate, the sterile toothed, the ribs scabrous. New Zeal, and Chatham Isl.

L. M. Underwood and Wilhelm Miller.