Research on native ornamental species from Mexico

Abstract

Mexico is known as a megadiverse country, and its flora includes about 25,000 described species of vascular plants. Many of these have been bred to be used as ornamentals, examples of which include the genera Ageratum, Begonia, Cosmos, Dahlia, Euphorbia, Helianthus, Tagetes, Tigridia, Polianthes and Zinnia, among many others. The number of plants already developed for ornamental purposes is relatively low compared with the great diversity found in Mexico. For this reason, at the Centro de Investigacion y Asistencia en Tecnologia y Diseno del Estado de Jalisco A.C., efforts are being directed to introduce new cultivars and species into culture to be utilized as ornamentals. Selections were made of suitable genera and species, some of which include geophytes, from the genera Bessera, Habranthus, Hymenocallis, Milla, Polianthes, Sprekelia and Zephyranthes, and some perennials such as Eustoma. Chromosome number determination has been performed for most of the species, revealing a polyploid complex in the genus Sprekelia, where the diploid chromosome number is 2n=2x=60, and triploid, tetraploid and pentaploid forms have been found. In the genus Polianthes, several species have been analysed, and all of them showed a bimodal karyotype, consisting of ten big chromosomes and 50 small ones (2n=2x=60). In Habranthus longifolius, the chromosome number ranged from 34 to 36, showing one, two or three B chromosomes. Hymenocallis howardii has 96 chromosomes. The genus Eustoma has a chromosome number of 2n=2x=72. In order to generate genetic variation, interspecific hybridization has been performed in the genus Polianthes and in the genus Eustoma, resulting in hundreds of hybrids, which are being selected for further breeding programmes. In this work, the species and breeding programmes are described.