Observations sur le pollen de quelques especes du genre Coffea et de certains genres voisins (Rubiacées)
Pollen grains of several species classified in the sections Eucoffea. Paracoffea and Mascaracoffea or in the genera Argocoffea, Argocoffeopsis and Calycosiphonia have been described. The pollen is generally tricolporate. It is however 4- or 5-colporate in Argocoffeopsis scandens and Argocoffea jasminoides. Coffea lebruniana, which does not possess pori nor colpi, is called "tetraporoid". The grains are subspheroidal and present sometimes a triangular outline. Their equatorial diameter varies from 26 to 31 ¿. The sexine of the studied pollen grains is generally thicker than the nexine, and particularly in Coffea lebruniana which presents a sexine at least four times thicker than the nexine. If the sexine is baculate in most of the studied species, it is however clavulate in Coffea melunocarpa, C. horsfieldiana and clavulate to reticulate in C. lebruniana. The bacula of the sexine are generally very close and the latter appears radially striated in cross-sections. In front-view, the heads of the bacula present a more less compact granulation (1.-0 pattern). The pollinic characters of Coffea melanocarpa differ totally from those of the genus Argocoffea from which this species must be withdrawn. Besides, they show a certain analogy with those of Coffea horsfieldiana which is classified in the section Paracoffea. The pollen of Coffea lebruniana distinguishes itself very clearly from all the other studied species. The remarkable differences are sufficiently important to be classed in a new section of the genus Coffea. There are no differential generic characters between pollen grains of Argocoffeopsis scandens and Argocoffea jasminoides
| Main Author: | |
|---|---|
| Format: | biblioteca |
| Published: |
May
|
| Subjects: | COFFEA, POLEN, OSPORAS, ANATOMIA DE LA PLANTA, HISTOLOGIA, |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|