Palinología de Agavaceae, una contribución biosistemática

The pollen of 15 genera and 36 species of the family Agavaceae were studied, based on Hutchinson' s classification. Observations were made with LM and SEM. Different taxonomical classifications are reviewed considering pollen morphology, geographical distribution, chromosome number and ovary position. From palynological point of view, Dahlgren et al., last classification agrees with the results obtained. Pollen samples studied show two levels of morphological behaviour: at an interespecific level there is little or no variation and at a generic level the following patterns are observed: a) semitectate and mainly monosulcate: Agave, Beschorneria, Dasylirion, Furcraea, Hesperaloii, Manfreda and Polianthes sometimes disulcate (Agavaceae, Agavoideae); b) tectate-perforate and monosulcate: Yucca (Agavaceae, Yuccoideae) and Dracaena americana (Dracaenaceae); c) tectate perforate to microreticulate and monosulcate to disulcate: Beaucamea, Calibamis and Nolina (Nolinaceae); d) intectate verrugate and monosulcate: Hasta (Funkiaceae); e) semitectate to tectate perforate and trichotomosulcate: Phormium (Phormiaceae); f) fosulate and monosulcate: Cordyline (Asteliaceae) and Dracaenafragans (Dracaenaceae) and g) psilate and ulcerate: Sansevieria (Dracaenaceae).

THE EFFECT OF OVULE POSITION ON THE FREQUENCY OF HYBRID AND INBRED SEED IN FABA BEAN

The effect of ovule and ovary position on the frequency of hybrid seed production of faba bean (Vicia faba L.) was measured at Dijon, France and Saskatoon, Canada. Even though there was far greater ovule fertilization frequency at Dijon (72%) than at Saskatoon (30%) the frequency of hybrid seed was significantly greater at Saskatoon (24%) than at Dijon (15%). Neither the position of the ovule within the ovary nor the position of the raceme on the stem had any effect on the production of hybrid seed. However, at both locations the highest position within a raceme produced a significantly greater proportion of hybrid seeds. It is proposed that under the effect of intra- or inter-plant stress, developing ovaries containing hybrid embryos may be selectively retained.Key words: Vicia faba, ovule fertilization, outcrossing, faba bean