Shoot Tip Abortion and Sympodial Branch Reorientation in Brownea Ariza (Leguminosae)

Abstract

The growth of the tropical tree Brownea ariza Benth. is modular and conforms to Troll's model. Distinctive anatomical features of its shoot development were investigated. Each module consists of from 6–10 compound leaves and terminates its growth by shoot tip abortion. Sympodial branch systems are formed by renewal growth from the most distal (pseudoterminal) 1–2 buds. New modules are wholly preformed within large (15–28 cm) buds. The flush occurs without a resting period and full shoot expansion is completed within one day. A distinct abscission zone develops in the stem just distal to the node of the last expanded leaf. Abortion of the shoot apex and 5–6 embryonic leaves occurs 2–3 days after the flush begins. This tissue vacuolates and begins to become necrotic prior to actual abscission. New flushes are pendent but are reoriented to a plagiotropic or upright position to create an arborescent form. Reorientation begins quickly (10° within 2 days) due to maturation of primary and secondary tissues and continues throughout the life of the branch by means of reaction wood formation on the upper surface.

Ecuadorian Brownea and Browneopsis (Leguminosae‐Caesalpinioideae): Taxonomy, palynology, and morphology

“…In (Brownea ariza =) Brownea grandiceps Troll's architectural model in the system of Hall6 & al. (1978) is evident in the seedling (Mueller 1988;pers. obs.…”

“…), as it also seems to be in the other Brownea species observed in this study. Bud-scale morphology of B. grandiceps is studied by Roth & Merola (1969) and by Mueller (1988 The synonymized species were also separated by a number of quantitative characters. Regarding these characters, the studied material shows continuous variations, which include all upper and lower limits, cited in the diagnoses of the synonymized species and in all the descriptions of B. grandiceps, except those of Velasquez (unpubl.)…”

“…The characters of Brownea and Browneopsis. 1: Mueller (1988); 2: Graham & Barker (1981); 3: Fasbender (1959); 4: Kalin Arroyo (1981); 5: Snow & Snow (1972); 6: J. T. Knudsen pers. comm.…”

Morphology and architectural analysis of Copaifera pubiflora seedlings (Detarioideae, Leguminosae)

“…As observed in other temperate and tropical trees (e.g., Foster et al, 2007; Millington, 1963; Mueller, 1988), seedlings of Copaifera pubiflora have a determinate growth since its shoot apex aborts after a short operative period (Barthélémy & Caraglio, 2007). As early as the E1 stage, the apical bud either did not grow or expanded into a poorly developed shoot that aborted within 1 or 2 weeks.…”

“…As early as the E1 stage, the apical bud either did not grow or expanded into a poorly developed shoot that aborted within 1 or 2 weeks. Such a condition in C. pubiflora is intermediate between what occurs in other legume species such as Brownea grandiceps Jacq., where the apex aborts within 1-2 days, and Gleditsia triacanthos L., where apex abortion may take several weeks (Mueller, 1988).…”