TENDRIL-CLIMBERS 



47 



production of a complete cylinder of wood l , while the stimulus acts as 

 far as the base of the tendril of Bauhinia causing its originally flattened 

 outline to become more or less circular 2 . 



The stimulus of contact causes the development of the disks by which 

 the tendrils of various species of Am- 

 pelopsis (Fig. 15), Bignonia capreolata, 

 B. liitoralis, Hanburya mexicana, Cissus 

 pauliniaefolia attach themselves to rocks, 

 walls, or the bark of trees 3 . These disks 

 may attain a considerable size, those of 

 Amphilobium mutisii often being 12 to 

 14 mm. in diameter, and 4 to 6 mm. 

 thick at the centre 4 . The tendrils of 

 this plant and Q{ Ampelopsis quinquefolia 

 may also twine around supports. 



The disks or suckers are usually 

 formed by outgrowths from the epi- FlG . , 5 Ampe i opst - s quinquffo i ia . The tendril 

 dermal cells and subjacent parenchyma, $ r jf { g attaching disks - and has become 

 but those of Amphilobium mtitisii^ 



contain vascular tissue, and often also an annular air-space around the 

 margin of the disk. By the aid of a sticky secretion, or by growing into 

 the irregularities of the supporting surface, so firm an attachment is often 

 produced that the tendril breaks before the disk is torn away. In the 

 tendrils of Ampelopsis Veitchii^ Vitis inconstans, and Cissus paulinaefolia the 

 suckers are preformed structures present as small swellings at the tips .of the 

 branched tendril and are simply excited to further development by contact, 

 but no such rudiments are present on the tendrils of Ampelopsis quinquefolia 

 and A mpkilobium mutisii. The suckers may be formed at various points on 

 the tendril, but in Ampelopsis usually, and in Amphilobium always, at the 

 tip of one or all of the branches if these are in contact with the support. 

 The three-armed tendril of Amphilobium is able to coil around a smooth 

 glass rod, but not to form suckers even where the tips of the branches 

 touch the glass 6 . When in contact with a rough surface the disks may 

 become perceptible in two or three days, but the full development of the 

 large disks of Amphilobium may take from one to two months. The 

 tendrils of most Cucurbitaceae show a certain proliferation of the epidermal 



1 For details on petiole-climbers cf. Derschau, Einfluss von Contact u. Zug auf rankende Blatt- 

 stiele, Leipziger Dissert., 1893. 



2 Ewart, I.e., p. 222. 



3 Mohl, Ranken- u. Schlingpflanzen, 1827, p. 70; Darwin, Climbing Plants; Pfeffer, Arb. d. 

 bot. Inst. in Wiirzburg, 1871, Bd. I, p. 95 ; Lengerken, Bot. Ztg., 1885, P- 48; Schenck, Beitrage 

 z. Biol. u. Anat. d. Lianen, 1892, I, p. 240. 



4 Ewart, 1. c., p. 219. 5 Id., I.e., pp. 219-20. * Id., 1. c. 



