Nov. 1003.] BOTANICAL SOCIETY OF EDIXBUltGIl 419 



XOTE ON THE FORMATION OF THE BULB IN WeST- 



AusTEALiAN Species OF DiiosEKA. By Alexandki; 

 Morrison', M.D. 



(Read 12th Xoveinbcr 1903.) 



The presence of more than one bulb on the rout of Drosera 

 hidhigcna^ suggested a closer examinntion of specimens, in 

 order to determine their mode of formation, especially of 

 the extra bulbs. The rootstock is seen to be covered with 

 the pale brown fibrous remains of the rhachis of the 

 previous year's plant, — the present axis being enveloped 

 in it from the bulb to the surface of the ground. A 

 moderate number of short horizontal roots, copiously 

 provided with hairs, spring from the rootstock, penetrat- 

 ing this fibrous sheath, while from its upper part — close 

 to the surface of the ground — proceed commonly one or 

 more long out-runners smooth and apparently of the same 

 structure as the rootstock itself, with occasionally a short 

 lateral root provided with hairs. Such long processes, or 

 stolons, are common on some Australian orchids, for 

 instance some species of Fterostylis, in which they 

 frequently end in bulbous swellings ; but in this species 

 of Drosera no distinct thickenings have so far been 

 observed. 



The majority of plants of D. htdhifjena have only one 

 bulb ; but two, three, or even four such are met with — 

 arranged in series, the one directly l)elow the other. At 

 about one inch belov/ the surface tlie rootstock expands 

 a.t its base into a .short conical body, closely applied to the 

 upper surface of the bulb, but continuous with it only by 

 means of a slender and very short pedicel. The bulb 

 itself is enveloped iri thick dark brown scales, and is 

 subglobular in form, flattened on the upper side, and 

 somewhat pointed below. It appears to have been de- 

 veloped from the enlarged extremity of the rootstock — 

 to which the name of pro-hulb may be given — by a 

 process of Inidding from its lower surface. In the ca.se of 

 a plurality of bulbs, the same budding process has taken 

 place in the formation of new bulbs, — each successive one 

 being formed on the end of a prolongation of tlie axis 

 ^ See page 1 . 



