BHAT, RAMAKRISHNA, B.* AND DARRELL, J. WEBER. Department of Botany, University of Transkei, Private Bag X1, Umtata, South Africa; Department of Botany and Range Science, Brigham Young University, Provo, Utah 84602-5181. - The significance of epidermal characters in the taxonomy of the Bombacaceae.
The epidermal structure, structure and ontogeny of stomata were
investigated in three species of the family Bombacaceae. Epidermal
cells are polygonal and isodiametric or elongated and irregular with
mostly straight, occasionally arched and rarely sinuous anticlinal
walls. The epidermal cells may contain drusses and pyramidal or
sphaero crystals of calcium oxalate. Mature stomata are evenly
distributed over abaxial side of the leaf surface in between the
veins, sometimes over the veins and finer veins. On the adaxial side
of the leaves stomata are distributed only on either side of the
midrib or secondary veins. Sometimes stomata are confined only to the
midrib region. More or less a definite pattern of arrangement and
orientation of stomata are noticed on the upper surface of the leaves.
They are oriented either parallel or oblique to the midrib or
secondary veins. The stomatal types observed are anisocytic,
paracytic, anomocytic and cyclocytic. The development of the
anisocytic and paracytic stomata conforms to the syndetocheilic or
mesogenous, while that of anomocytic and cyclocytic stomata to
haplocheilic or perigenous type. Aberrant types such as degeneration
of stomata, juxtaposed contiguous stomata, obliquely oriented stomata,
and stoma with a single guard cell were observed. Stomatal and
epidermal cell frequency per millimetre square and stomatal index are
also tabulated. The epidermal characters of the species examined here
show a remarkable difference from the members of the family Malvaceae.
The separation of the family Bombacaceae from Malvaceae is justified.
Key words: Anatomy, Bombacaceae, epidermal characters, ontogeny, stomata, taxonomy