Encyclopaedia of Gardening 243 



genus, comprising one or two very pretty hardy herbaceous plants. 

 Linifolia, a hardy annual, with white flowers, is the Venus' s Navel- 

 wort; it grows about 9 ins. high. The same popular name is often 

 applied to verna, a dwarf spring-blooming perennial with blue 

 flowers in March. Luciliae is a charming blue summer-blooming 

 Alpine for rockeries (see the Botanical Magazine, t. 6047). They 

 can be raised from seeds in spring, the perennials also by division; 

 they are not particular as to soil. 



Oncidium (oncid-ium, from ogkos, a tumour, in allusion to the 

 growths on the lip. Ord. Orchidaceae) . A large and attractive 

 genus of Orchids, comprising some 300 species, with a large number 

 of varieties and hybrids. They are allied to the Odontoglossums, 

 and the cultural remarks made under that subject apply to Onci- 

 diums, but the species with leathery leaves need less water when 

 the growth is complete, and only enough should be given to keep 

 the pseudo-bulbs from shrivelling. They differ a good deal in 

 respect to heat requirements, and any one who desires to grow a 

 collection should consult a special modern work on Orchids. The 

 following are a few of the principal species: Concolor, yellow, 

 May bloomer, cool house (Botanical Magazine, t. 3752). Crispum, 

 brown, summer and winter, cool house (Bot. Mag., t. 3499). For- 

 besii, brown, margined yellow, autumn, cool house (Bot. Mag., 

 t- 375)- Kramerianum, brown and yellow, spring, hothouse. 

 Macranthum, spring, brown, purple, white, and yellow, cool house. 

 Marshallianum, yellow and brown, summer, cool house. Papilio, 

 red and yellow, spring, hothouse (Botanical Register, t. 910). 

 Phalaenopsis, white, purple, and violet, cool house. Sarcodes, 

 brown and yellow, spring, intermediate house. Tigrinum, yellow, 

 barred brown, cool house. 



Onion. See Kitchen Garden. 



Onoclea (onocle-a, the Greek name. Ord. Filices). A small 

 genus of hardy ferns, the finest member of which is Germanica, the 

 Ostrich Fern, also known as Struthiopteris Germanica. This is a 

 noble plant for a sheltered place near the margin of a stream, where 

 its stoloniferous roots can ramble in moist soil. It can be propa- 

 gated by divisions of these roots. Sensibilis is a much smaller 

 species, growing only about 2 ft. high. 



Ononis, Rest Harrow (ono-nis, from onos, an ass, and onemi, to 

 delight, in reference to the ass's enjoyment of it as food. Ord. 

 Leguminosae) . Two or three members of this large genus are worth 

 growing in the rock garden, notably arvensis, the Rest Harrow, 

 which produces rose and white flowers in summer on stems a few 

 inches high ; rotundif olia, a dwarf shrub with rose flowers in summer 

 (see the Botanical Magazine, t. 335), and the fine variety of the 

 latter called splendens. They are not particular as to soil, and are 

 easily raised from seed in spring, when the perennials may be 

 divided. 



Onosma, Golden Drop (onos-ma, from onos, an ass, and osrna* 

 small, in reference to its attraction for the ass. Ord. Boragineae). 

 A small genus of charming hardy rock plants, the most graceful of 



