OSMUNDA—Cinnamon Fern, Royal Fern, Interrupted Fern
Evergreen or leaflosing (deciduous) Ferns which are wild in Japan, North America, the West Indies, northern Asia, and Europe. Those cultivated in North America are all hardy. They grow from 18 in. to 8 ft. in height, and have pinnate (feathery) fronds; the spores are borne on separate leafless spikes, or on spikes on the ends of the fronds.
The best kind is O. regalis, the Royal Fern. This is found growing wild in many parts of the world, as well as in North America. It grows in swampy places and, under favorable conditions, reaches 8 ft. in height. Other hardy kinds are O.
cinnamomea, 2-5 ft., and O. Claytoniana, 3-6 ft.; both are natives of North America. Their roots provide the Osmunda fiber which is used for potting epiphytic orchids. The name Osmunda is derived from Osmunder, one of the names of Thor.
Garden Treatment. Osmundas will grow in a sunny or partially shaded position, and require abundance of moisture at the roots. These Ferns do best on the margins of a stream or pond, or in a bog garden, but can be grown in beds or borders provided the soil is kept moist in summer.
Deep, Moist Soil Is Necessary. When planting on the edge of a pond or stream, very little preparation is necessary, as the roots are abundantly supplied with water. In drier situations, however, success can only be assured by taking precautions to keep the soil moist. Take out the soil to a depth of 2 ft. and 2 ft. in diameter, for a single plant, or correspondingly larger for more plants. Puddle the bottom and sides with clay or make them watertight with cement and fill the hole with a mixture of equal parts of loam, leaf mold and peat. Planting is done in early spring, and the crowns of the plants are set just above the level of the soil.
Once planted, they need very little attention, so long as they have access to sufficient moisture. A top-dressing of rich compost in April is beneficial, and the dead fronds should be removed at the same time. It is unwise to remove these fronds in the autumn as they form a natural protection for the crowns.
Propagation is principally by spores. The plants may be increased by division, but they take a long time to recover from the disturbance. The spores may be sown as soon as they are ripe or they may be stored and sown at a later date. The spore-bearing spike is gathered when the spores are fully developed. The spores of Osmunda regalis and its varieties are green when they are ripe. The spike is placed in a paper bag, which is hung in a dry, airy room or shed for 48 hours; the ripe spores will then be at the bottom of the bag.
Sowing Spores. The spores are sown in 5-in. pots; or in shallow seed pans, if large quantities of plants are required. They are well drained and filled with finely sifted compost, and a little charcoal dust is sprinkled on the surface. The soil is moistened by immersing the vessel in water until bubbling ceases; then it is placed aside to drain and the spores are sprinkled thinly on the surface. The spores are not covered with soil, but a pane of glass is laid over the pot or seed pan, which is set in a saucer, and this is kept filled with water.
The spores take several weeks to germinate. When the young plants appear on the surface, they form a green mosslike growth made up of thin green, heart-shaped structures, which eventually attain to 1/2 in. in diameter. When these are fully grown, the fronds commence to develop. At this stage, or before, if they are overcrowded, they are pricked off, 1 in. apart, into seed pans filled with finely sifted compost. The soil is moistened, and they are shaded from sunlight. When large enough, they are potted in 3-in. pots, and subsequently in larger ones.
The Chief Kinds. Among these are O. regalis (Royal Fern), 8 ft., and its varieties—cristata, with crested fronds; gracilis, a slender form with bronze-tinted fronds; and palustris, 3 ft., young fronds light green, older fronds, reddish. Also, O. cinnamomea (Cinnamon Fern), 4 ft.; and O. Claytoniana (Interrupted Fern), 3 ft. The measurements refer to the length of the fronds.