184 



DOMESTIC BOTANY. 



rooted orchids yield salep, which is largely used as food by 

 the natives. 



Eock Lily {Dendrohium speciosum). A native of New 

 South Wales, growing upon rocks. It has large pseudo- 

 bulbs, the size of cucumbers, which are said to be eaten by 

 the natives. It has a long spike of white showy flowers. 

 New South "Wales contains a large number of terrestrial 

 species, all of which are both beautiful and interesting. 



With regard to the fertilization of the ovary of orchids 

 early botanists entertained two different opinions ; one that 

 the fertilizing essence of the pollen passed through the caudi- 

 cula and gland to the stigma ; the other that the pollen came 

 in direct contact with the stigma, as is the case in ordinary 

 flowers. After many experiments carried on for several years 

 on plants under my notice at Kew by the "Prince of Bota- 

 nists," Dr. Eobert Brown, he in 1833 published the result 

 of his observations, proving the latter to be the correct view, 

 the principles of which I have briefly explained at page 32. 

 But with regard to orchids it is necessary to explain the im- 

 portant part performed by the gland ; in general its size and 

 form may be compared to a small teat or pin-head, which on 

 being touched by the finger, pencil-point, or the like, it ad- 

 heres, and on moving the hand the attached pollen-masses 

 are drawn out from under the operculum. On applying a 

 pollen-mass to the moist surface of the stigma it immediately 

 adheres and becomes absorbed. Soon after this, the aspect 

 of the flower changes ; the splendid flowers of Cattleyas be- 

 gin to fade the following day ; others change colour, and in 

 some the parts of the flower increase in size ; but the most 

 important effect is that produced on the ovary, which gra- 

 dually increases in size, and in time becomes a capsule with 

 perfect seeds. With very few exceptions the fertilization of 

 orchids does not take place without artificial aid ; in nature 

 the chief operators being insects, by the gland adhering to 

 their bodies, and with the pollen-masses are conveyed from 

 flower to flower, and by the movement of the insect in the 

 flower the pollen thus comes in contact with the stigmas. In 



