Annual cycle of shoot development in sugar maple

Abstract

Cytohistology and the development and morphogenesis of sugar maple (Acersaccharum Marsh.) shoots were studied. Three types were recognized: short shoots, long shoots entirely preformed in the bud (Epf long), and long shoots partially preformed in the bud (heterophyllous). The three shoot types varied not only in the size and number of internodes and leaves but also in the development of terminal buds. Terminal bud formation was delayed in heterophyllous shoots but because of a shorter plastochron, which extended later into the growing season, the terminal apices of these shoots were able to annually produce more primordia than in other shoot types. The beginning of embryonic shoot formation, however, began about the same time (late July) for all shoot types.

Response to an ozone gradient of growth and enzymes implicated in tolerance to oxidative stress inAcer saccharum(Marsh.) seedlings

“…However, young seedlings, saplings, and young and vigorous branches of mature sugar maple may have an episodic growth pattern [6,18,48] In this study, budbreak occurred in mid May prior to setting the seedlings into the chambers. The two seasonal patterns of shoot growth were observed among the seedlings.…”

“…These seedlings with two flushes will be referred to as "episodic" seedlings. The first flush of leaves will be hereafter referred to as the preformed flush, consisting of preformed leaves and the second flush as neoformed flush consisting of neoformed leaves as described by Gregory [18].…”

“…It is a shade tolerant, slow growing species [3]. Mature sugar maple trees have been described as a fixed growth species but young and vigorous sugar maple seedlings may have an episodic growth strategy with production of a second flush of leaves [6,18].…”

Response of Acer saccharum seedlings to elevated O3 and CO2 concentrations

“…However, in favourable environmental conditions, vigorous seedlings may develop a second flush of leaves (Gregory 1980). The environmental conditions of the study were such that no nutrient or light limitation should have occurred.…”

“…These seedlings with two flushes will be referred to as "episodic" seedlings. The first flush of leaves will be hereafter referred to as the preformed flush, consisting of preformed leaves, and the second flush as neoformed flush, consisting of neoformed leaves as described by Gregory (1980). The two types of seedlings were analyzed separately.…”