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98 ROBERT TRACY JACKSON ON 



Ampelopsis TRicrspiDATA. The Japanese Ivy, AmpeJopsis trinispldata Sieb, and 

 Zucc. (J[. veltchii Hort.), which is extensively cultivated as an ornamental vine, presents 

 striking features. In the seedling (PI. 17, fig. 20) the cotyledons are broadly ovate, 

 entire. The nepionie leaves are trifoliolate and alternate. The individual leaflets of these 

 nepionic leaves are irregularly ovate and dentate. It is noticeable that lateral leaflets 

 conform in outline to the shape of the terminal leaflet, and also that dentations are absent 

 in those portions of the leaflets which lie adjacent to one another, as in .1. quincpiefolia. 

 This trifoliolate stage is retained for a considerable period, through the first year's growth 

 in the specimens observed. In seedlings of the second year's growth, trifoliolate leaves 

 occur on the proximal part; but beyond them the leaves (PI. 17, fig. 21) are unifoliolate. 

 subcordate, deeply denticulate. This form of leaf is retained throughout the second year. 



In adult Ampdop)sli< tricuspldata localized stages in development are very marked. 

 At the base of the vine, and to a distance of three or four feet from the root, all the leaves 

 are trifoliolate (PI. 17, figs. 23, 25), repeating in form the nepionic leaves of the seedling 

 (PL 17, fig. 20). No trilobed or cordate unifoliolate leaves are found at this area in vines 

 raised from seed. In vines raised from cuttings, as is frequently done, the leaves at this 

 area do not have the trifoliolate character, but are unifoliolate and trilobed. I am informed 

 by a nurseryman that he adopts the method of propagating by cuttings to gain uniformity 

 in the leaves of the vine. The occurrence of typical nepionic leaves at this area is in entire 

 accord with what is shown in regard to suckers from the base in many plants; namely, 

 that at the nepionic area there is a tendency to produce nepionic leaves throughout the 

 life of the individual. Beyond the trifoliolate leaves at the base, all the leaves on the old 

 wood (preceding the current season's growth) are unifoliolate and trilobed (PI. 17, figs. 22' 

 25), this being the " character" leaf of the species. In an adult in the current season's 

 growth, still a third type of leaf is found. This is cordate, deeply toothed (PL 17, figs. 

 24, 25), and repeats the form wliidi is characteristic of the second nepionic stage of the 

 seedling (PL 17, fig. 21). The leaves of the adult in this species, which at first sight 

 appear to be simple, should be considered compound leaves, reduced to a single leaflet. 

 The truth of this is evinced by the fact, that, when the leaves drop in the autumn, an 

 articulation develops, and the leaves separate from the petiole at the proximal border of 

 the blade. The petiole may remain in place for a considerable time after the fall of the 

 single leaflet. The trifoliolate leaves at the base of the vine separate from the petiole in 

 a similar iruinner, but leave three scars at the distal end of the petiole instead of a single 

 one. 



Ampelopsis triciispndata may fairly be considered a regressive species, in which the 

 unifoliolate character is developed by dropping out the two lateral leaflets from the proxi- 

 mal portion of the leaf. In the adult, when the leaves come out in spring, those at the 



