The morphology of the vegetative shoot apex and stem of some southern African Pavetta species

Structural, Functional and Phylogenetic Aspects of the Colleter

“…They develop quickly into multicellular branched trichomes consisting of a central stalk two to four cells thick from which radiate a number of relatively short branches. Horner and Lersten (1968) and Fahn (1979) reported the absence of cuticle on the dendroid colleters, but Herman et al (1986) demonstrated a very distinct cuticle by using Sudan Black B. This is in accordance with observations by Krause (1909), Faber (1912) and Uphof (1962).…”

“…The developing meristem is totally covered with colleter exudates which protect the meristem (Williams et al, 1982;Dave et al, 1988;Thomas and Dave, 1989o-c). In some species of Rubiaceae and Myrsinaceae the mucilaginous exudates contain bacteria (Boodle, 1923;Humm, 1944;Centifanto and Silver, 1964;Van Hove, 1972;Lersten, 1972;Lersten and Horner, 1976;Gardner et al, 1981;Miller et al, 1983aMiller et al, , b, 1984a, and may act as a medium for leaf nodule symbionts to enter the substomatal cavities (Dexheimer and Guenin, 1981;Herman, 1983;Herman et al, 1986); they may also maintain and nourish the bacterial colonies in the delicate and sensitive parts of the symbiotic life-cycle, where the bacteria are external to the host tissue (Miller et al, 1984ft).…”

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“…Here, the microscopic stem image shows that the pericyclic fibers have occurred as a continuous ring with a wavy outline, but in root anatomy, it shows a group of fibre and seen in the outer cortex region. Various types of calcium oxalate crystals have been seen in cortex region of both stem and root and also in the ground tissue of leaves; hence the presence and shape of crystals and the occurrences of two or more type crystals might be useful for taxonomic classification 27,28 . These crystals have been located in various tissue such as epidermis, phloem, xylem, pith and cortex 29 .…”

Flowering Plants of Africa: A Magazine Containing Colour Plates with Descriptions of Flowering Plants of Africa and Neighbouring Islands

“…The very young developing leaves in the growth point have already fully developed stomata on their upper (adaxial) surface but none on the lower (abaxial) surface where they occur in the mature state. The mucilage containing the bacteria enters the young leaves through these stomata on the adaxial surfaces from where the bacterial nodules develop in the leaves (Herman et al 1986;Herman 2007). In other experiments, the seeds were treated with boiling water in an effort to kill the bacteria.…”