Morphological Characterization of Three Intergeneric Hybrids Among Gloriosa superba ‘Lutea’, Littonia modesta, and Sandersonia aurantiaca (Colchicaceae)

Abstract

Three intergeneric hybrids among colchicaceous ornamentals, Gloriosa superba ‘Lutea’ (2n = 2x = 22), Littonia modesta (2n = 2x = 22), and Sandersonia aurantiaca (2n = 2x = 24), were subjected to morphological characterization and chromosome observation. Hybrid plants produced flowers 2 to 3 years after transplantation of ovule culture-derived plantlets to the greenhouse. All the hybrid plants, L. modesta × S. aurantiaca, L. modesta × G. superba ‘Lutea’, and S. aurantiaca × G. superba ‘Lutea’, showed a climbing habit like those of L. modesta and G. superba ‘Lutea’. Plants of L. modesta × S. aurantiaca and L. modesta × G. superba ‘Lutea’ were taller and shorter than their respective parents, whereas plant height of S. aurantiaca × G. superba ‘Lutea’ was nearly intermediate between the parents. Leaves of all the hybrids had a tendril at the tip like those of L. modesta and G. superba ‘Lutea’. Flower morphologies of all the hybrids were nearly intermediate between the parents. Flower colors of all the hybrids were similar to the seed or pollen parent. Although hybrids of L. modesta × G. superba ‘Lutea’ showed low pollen fertility as assessed with acetocarmine staining, the other two kinds of hybrids had nondehiscent anthers or no fertile pollen grains. Chromosome observation in root tip cells revealed that all the hybrids had a diploid number of chromosomes: L. modesta × S. aurantiaca (2n = 2x = 23), L. modesta × G. superba ‘Lutea’ (2n = 2x = 22), and S. aurantiaca × G. superba ‘Lutea’ (2n = 2x = 23). Novel morphological characteristics of the hybrids may be valuable for future breeding of colchicaceous ornamentals.