The relationship between size of shoot apices and morphological features of mature leaves and stems of four species of angiosperm trees
1993
Bostrack, J.M.
Shoot apex, leaf and stem growth parameters for four species of deciduous trees were measured. Only in elm was there a correlation between the size of shoot apical meristems and mature leaves. In ash, basswood and cottonwood there was no significant difference between size of shoot apices of sucker and canopy branches, despite significant differences in lamina size. In the sucker branches of all species studied there occurred an early, lateral expansion of the subapical region of the shoot apical meristem. This correlated well with the greater diameter of stem and pith regions of sucker branches. In addition, the season's annual ring of xylem was greater in basswood, cottonwood and elm. Diameters of vessel elements were greater in sucker than canopy branches in three of the four species. Total branch and internode length and number of nodes per branch were significantly greater for sucker branches than canopy growth of all species studied. A hypothesis is proposed to explain the development of the very large surface area of leaves on sucker branches. This hypothesis is based on the position of sucker branches in relation to the root system and involves differences in water stress known to be present in all plants.
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