Étude au microscope électronique à balayage de la bulbille de Huperzia selago (L.) Bernh. (Lycopodium) : méristème apical, initiation foliaire et phyllotaxie

Abstract

R e~u le 17 juin 1981 VINDT-BALGUERIE, E. 1982. Etude au microscope Clectronique A balayage de la bulbille de Huperzia selago (L.) Bernh. (Lycopodium): mCristkme apical, initiation foliaire et phyllotaxie. Can. J. Bot. 60: 667-673. L'apex de la bulbille du Lycopode Huperzia selago (L.) Bernh. (Lycopodium) a Ct C CtudiC au microscope Clectronique A balayage. Du point de vue ontogCnique, des variations de la forme et de la taille du mCristkme apical ont CtC observkes: celui-ci, au cours du plastochrone, passe par des phases successives d'aires minimale et maximale. Grdce au microscope Clectronique A balayage, l'aspect quantitatif du problkme (surface et nombre de cellules) peut aussi Ctre abordC. I1 a CtC dCmontrC qu'au point vCgCtatif de la bulbille mGre les feuilles sont initiCes une A une et sont disposCes selon deux hClices. VINDT-BALGUERIE, E. 1982. Etude au microscope Clectronique A balayage de la bulbille de Huperzia selago (L.) Bernh. (Lycopodium): mCristkme apical, initiation foliaire et phyllotaxie. Can. J. Bot. 60: 667-673. The shoot apex of the bulbil of Huperzia selago (L.) Bernh.(Lycopodium) has been examined by scanning electron microscope. From an ontogenic point of view, changes in shape and size have been observed in the apical meristem. Successive minimal and maximal areas of this meristem are described during a plastochron. Area and cell number are also quantified with the scanning electron microscope. Only one leaf is initiated at the beginning of each plastochron, and the two contact parastichies observed in the shoot apex of the mature bulbil are two foliar helices.

Diversity of phyllotaxis in land plants in reference to the shoot apical meristem structure

“…These patterns are unrelated to shoot type (e.g., vegetative shoots, strobilus), although higher numbers of contact parastichies are generally observed in the plagiotropic axes. Notably, Fibonacci sequences do not predominate in the lycopods, but in fact occur at a relatively low (typically <1%) frequency [31,32]; however, Fibonacci sequences do repeatedly occur in the early developmental stages of vegetative gemmae (bulbils) in Huperzia selago [33], but are transformed to a non-Fibonacci pattern in later stages of gemmling development. Interestingly, the multijugate patterns, which are quite common in the seed plants, have not been reported so far in the lycopods.…”