Xlviii APPENDIX. 



Drummond says, that " the bulb is renewed every year in 

 the centre of" several layers of bark-like substance, one of 

 which layers is added every year by the decay of the old 

 bulb. If the young bulb is dissected at the time when the 

 plant is in flower, the layer of fibrous substance, which after- 

 wards becomes the covering, is easily perceptible ; it termi- 

 nates in a point, which the following season becomes a root, 

 and another root is produced from the bottom of next year's 

 flower-stalk. In planting these roots the fibrous substance 

 should not be removed, or the plant will not thrive. The 

 layer can be easily traced back for ten or twelve years, and 

 I have no doubt that many of these Orchid aceae have con- 

 tinued to flourish in half a square inch of earth for ages." 

 " These coated species grow mostly on the exposed sides of 

 hills, where the soil is a strong loam, mixed with a large 

 proportion of gravel, and where their numerous coats must 

 be of the greatest use in protecting their roots from the ex- 

 cessive heat of the summer sun. AH the time they appear 

 aboveground the weather is seldom warmer than in England 

 in the month of May." Such plants as Caladenia (fig. 3 & 3*) 

 deviate a little from this manner of growth, their roots form- 

 inof knots, analowus to those on the roots of Arrhenatherum 

 avenaceum, and ought, Mr. Drummond thinks, to be con- 

 sidered rather as reservoirs of nourishment, to enable the 

 plant to flower and perfect seeds, than as true bulbs or buds. 

 " Young plants may be produced by dividing the roots ; but 

 they spring from the joints between the swellings of the 

 root. One of these swellings, or tubers, is produced annu- 

 ally, or more than one when the root becomes forked, as it 

 sometimes does." This description applies only to Glossodia 

 and Caladenia, the species of all which seem to have the 

 same natural habit. 



Another plan of growth is to form a bulb at the end of 

 long woolly roots, as in Drakcea (fig 5 &: 7), Caleana (fig. 4), 

 and Leptoceras (fig. 8) ; and this sometimes takes place in an 

 excessive degree, as is shewn at fig. 6, where a a are the new 

 bulbs, and b the mother which brought them forth. Mr. 

 Drummond has traced them in one species for more than a 

 foot. 



The same collector speaks thus of what he supposes to 

 be a Diuris, and which, from the figure given (9), seems to 

 be of that genus ; but the description does not apply to it. 



