Embryo Development and Anatomy in Araucaria Juss

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Abstract
Embryo development following suspensor elongation was studied in three species of Araucaria: A. cunninghamii, A. heterophylla and A. bidwillii. The mature embryos of these species were compared with those of A. hunsteinii and species for which published data are available. In general outline, the embryogeny of Araucaria resembles that described for a number of other conifers. Differences are evident among species of Araucaria with respect to the following features of the mature embryo: overall size; relative lengths of the cotyledons, hypocotyl and root cap; cotyledon number; the presence of stomates; the extent and arrangement of the vascular and secretory tissues; and the state of differentiation of the vascular tissue. Consideration of all these features lends some support to the generally recognized division of the genus into four sections, although there is some evidence to suggest a relationship between the Eutacta and Intermedia species, on one hand, and the Columbea and Bunya species, on the other.