LEAF-CLIMBBBS. 35 



phgllum, T. peregrinum, T. elegans, T. tuberosum, and a dwarf 



variety of, as I believe, T. minus. 



Tropceolum tricolorum, var. grandijlorum. — The flexible shoot, 

 which first rises from the tuber, is as thin as thin twine. One 

 such shoot revolved in a course opposed to the sun, at an average 

 rate, judging from three revolutions, of 1 h. 23 m. ; but no doubt 

 the direction of the revolving movement is variable. When the 

 plant had grown tall and much branched, all the many lateral 

 shoots continued to revolve. The stem, whilst young, twined regu- 

 larly round a thin vertical stick ; in one case I counted eight spiral 

 turns : but when grown older, the stem often runs straight up for 

 a space, and, being arrested by the clasping petioles, makes one or 

 two spires in a reversed direction. Until the plant has grown to 

 a height of two or three feet, about a month after the first shoot 

 lias appeared above ground, no true leaves, but in their place little 

 filaments, coloured like the stem, are produced. The extremities 

 of these filaments are pointed, a little flattened, and furrowed on 

 the upper surface. They never become developed into leaves. 

 As the plant grows in height new filaments are produced with 

 slightly enlarged tips ; then others, bearing on each side of the 

 enlarged medial tip a rudimentary segment of a leaf; and soon 

 other segments appear, until a perfect leaf is formed with seven 

 deep segments. So that on the same plaut we may see every step 

 from tendril-like filaments to perfect leaves. Hence this plant, 

 whilst young, might be classed with tendril-bearers. After the 

 plant has grown to a considerable height, and is secured to its 

 support by the clasping petioles of the true leases, the clasping 

 filaments on the lower part of the stem wither and drop off; so 

 that they perform only a temporary service. 



These filaments, as well as the petioles of the perfect leaves, 

 whilst young, are highly sensitive on all sides to a touch. The 

 slightest rub causes them to curve towards the rubbed side in 

 about three minutes : one bent itself into a ring in six minutes ; 

 they subsequently became straight again : if, however, they have 

 once completely clasped a stick, when this is removed, they do not 

 recover themselves. The most remarkable fact, and which I have 

 observed in no other species of the genus, is that the filaments 

 and petioles of the young leaves, if they catch no object, after 

 standing in their original position for some days spontaneously 

 and slowly move, oscillating a little from side to side, towards the 

 stem of the plant. Hence all the petioles and filaments, though 

 arising on different sides of the axis, ultimately bend towards and 



D 2 



