Abstract Detail

Anatomy and Morphology

Luna Márquez , Lorena [1], Pace, Marcelo [2].

Ontogeny and phylogenetic distribution of the lobed stem cambial variant within the pantropical genus Byttneria (Malvaceae s.l., Byttnerioideae).

Byttneria is a pantropical genus of mostly climbing plants. Some of the species are known for having non-cylindrical, lobed stems. However, to date no one has studied how these stems are ontogenetically formed or how they have evolved in the genus. Applying traditional anatomical methods, we described the ontogeny of lobed stems using B. divaricata as a model. Through a literature and herbaria survey we reviewed the presence of lobed stems within the genus and explore the evolution of this cambial variant within the phylogenetic context of Byttneria and allies. Lobed stems in B. divaricata are 5-lobed since primary growth, and each lobe coincides with one of the five vascular bundles present in the stem. By differential activity of a single continuous vascular cambium, secondary growth sharpens the lobed shape present originally. Typically, two of the five lobes merge into four lobes at a node. On a finer scale, secondary tissues in B. divaricata share common characters with other Malvaceae, such as tile-cells in xylem and wedge-shaped dilated rays in phloem. It is known that Byttneria is not monophyletic and other authors have recovered two clades within the genus. Within these two clades, Byttneria s.s exhibits lobed adult stems, while clade Vahihara lacks them. Both clades have climbers, each one with different climbing mechanisms. Byttneria s.s. has leaning shrubs that usually have lobed stems, which are armed with prickles. Clade Vahihara on the other hand is composed of twining lianas with cylindrical stems and no prickles. Here we evidence one of the few cambial variants in the literature whose secondary body directly reflects the vasculature of the primary body and show that the lobed stems have a strong phylogenetic signal within Byttneria and related genera.

1 - Universidad Nacional Autónoma de México, Instituto de Biología, Botánica , Circuito Zona Deportiva s/n de Ciudad Universitaria, Coyoacán , Mexico City, 04510, Mexico
2 - Instituto de Biología, Universidad Nacional Autónoma de México, Circuito Zona Deportiva s/n de Ciudad Universitaria, Coyoacán, Mexico City, DF, 04510, México

climbing plants
cambial variant
lobed stems

Presentation Type: Oral Paper
Session: AM1, Anatomy and Morphology
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 2:00 PM
Number: AM1016
Abstract ID:708
Candidate for Awards:None

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