THE RECIPROCAL INFLUENCES OF STOCK AND CION 561 



Burbidge,^® worked on C. Boursieri, grows erect, while on Biota or Thuya, 

 or if grown from cuttings, it spreads horizontally on the ground. The 

 same writer quotes Briot to the effect that the Lihocedrus tetragona is 

 changed from a narrow cyUndrical column to a wide-spreading form by 

 working on Saxegothcea. 



Among fruit plants, the plum and peach have been cited as showing 

 in the habit of their tops the influence of the stocks on which they are 

 growing. 



Knight**^ described this influence: "The form and habit which a 

 peach tree of any given variety is disposed to assume, I find to be very 

 much influenced by the kind of stock on which it has been budded; if 

 upon a plum or apricot stock, its stem will increase in size considerably, 

 as its base approaches the stock, and it will be much disposed to emit 

 many lateral shoots, as always occurs in trees whose stem tapers consider- 

 ably upwards: and, consequently, such a tree will be more disposed to 

 spread itself horizontally, than to ascend to the top of the wall, even when 

 a single stem is suffered to stand perpendicularly upwards. When, 

 on the contrary, a peach is budded upon the stock of a cultivated variety 

 of its own species, the stock and the budded stem remain very nearly 

 of the same size at, as well as above and below, the point of their junction. 

 No obstacle is presented to the ascent, or descent, of the sap, which 

 appears to ascend more abundantly to the summit of the tree. It also 

 appears to flow more freely into the slender branches, which have been 

 the bearing wood of preceding years; and these extend themselves very 

 widely, comparatively with the bulk of the stock and large branches." 



Comparing the growth of the Milton plum on various stocks, Waugh^^^ 

 reported: "The trees of this variety growing on Wayland roots are 

 upright narrowly vase-form, with relatively few large branches. They 

 are almost as narrow headed as typical trees of Abundance or Chabot. 

 On Marianna roots, in the very next row, the trees of Milton are low, 

 round-headed, bushy, with thick-spreading, drooping tops, much Hke 

 trees of Marianna. If anything, they exaggerate the typical character 

 of the Marianna head. Moreover, the leaves are several shades darker 

 and glossier and the twigs are dark red instead of being green as in trees 

 of the same variety growing on Wayland roots. On Americana Milton 

 has almost the same characters as on Wayland." 



Somewhat later Stewart,^^^ describing these same trees, wrote: "At the 

 present time the differences in color of foHage and bark of young twigs are not 

 noticeable, neither is the ' upright narrowly vase-form ' head of Milton on Way- 

 land anywhere near so pronounced. Notwithstanding these modifications, how- 

 ever, there is still a marked difference in the habit of growth of the trees upon 

 Wayland and Marianna stocks. On Wayland the habit of growth is more or 

 less upright, whereas on Marianna the head is low, bushy and spreading. Doubt- 

 less, as the trees grow older, these differences will tend to become less marked." 



