Development of the seed of Trichilia grandifolia Oliv. (Meliaceae)

The ovule of Trichilia grandifolia is bitegmic, anatropous and crassinucellate with a massive chalaza and thick outer integument. After fertilisation a pachychalaza develops which ultimately constitutes about 2/3 of the bulk of the seed. The integuments form the remaining part of the seed coat. The outer integument is strongly multiplicative and becomes much thicker than the inner one, which in the mature seed can be distinguished as a thin, crushed layer. The whole sarcotestal seed coat contains a plexus of vascular bundles in the inner layer of the outer integument and of the pachychalaza. Along the raphal side no distinct inner integument can be discerned in part of the ovules and pre-raphe bundles run towards the top of the inner integument. A derived condition of the seed is indicated.