Floral Morphology of Three Species of Gaultheria. Contribution from the Hull Boanical Laboratory 638

Abstract

1. Various aspects of the floral morphology of Gaultheria procumbens L., G. ovatifolia A. Gray, and G. shallon Pursh are presented. 2. These three species of Gaultheria agree with most members of the Ericaceae in being pentacyclic (the outer cycle of stamens opposite the petals), pentamerous, actinomorphic, sympetalous, hypogynous, and perfect. The fruit is a loculicidal capsule covered by a fleshy calyx, a character used taxonomically to place the genus, with three others, in a separate tribe of the Arbutoideae. 3. In the receptacle the vascular cylinder gives rise to a whorl of five sepal bundles, a whorl of five petal-petalad stamen bundles, a whorl of five sepalad stamen-septal carpel bundles, and a whorl of dorsal carpel bundles (arising independently in G. procumbens and G. ovatifolia but in common with the petalpetalad stamen supply in G. shallon). The remaining vascular bundles form the ventral supply of the carpels. The single sepal bundle is undivided in the receptacle of G. procumbens but divides into three in the other two species. Stylar bundles are continuations of only the dorsal bundles except in G. ovatifolia where the septal bundles also continue into the style. 4. The introrse anthers are awned in all three species, though the awns are small and disappear early in G. ovatifolia. The general anther structure, microsporogenesis, and mature pollen are similar to those in most members of the Ericales. 5. The ovules in the three species are unitegmic, tenuinucellate, and essentially anatropous. Megagametophyte development is of the Normal (Polygonum) Type. Antipodals are large and persistent. 6. The endosperm is cellular and forms both micropylar and chalazal haustoria, which are large in G. procumbens, small in G. ovatifolia. The first division of the zygote is transverse. A suspensor is formed which places the young embryo within the main body of the endosperm. 7. A comparison of morphological characteristics between the Gaultherieae, as exemplified by these three species, and members of the Andromedeae show no new significant differences. 8. Morphological differences among the three species show a slight corroboration of Airy-Shaw's taxonomic separation of them into three different sections.