CIRCUMSCRIPTION OF CODONOPSIS AND THE ALLIED GENERA CAMPANUMOEA AND LEPTOCODON (CAMPANULACEAE, CAMPANULOIDEAE) .1. PALYNOLOGICAL DATA

摘要

Pollen from 23 accessions of Codonopsis and the allied genera Campanumoea and Leptocodon was examined via light microscopy, scanning electron microscopy, and transmission electron microscopy. All grains examined were of four types. Type I grains (found in all accessions of Campanumoea sect. Campanumoea, Codonopsis subg. Codonopsis, and Leptocodon) were oblate sphaeroidal, circular in polar outline, 4-10-colpate, with long colpi, short spinules, and thin nexine. Type II grains (found in all accessions of Campanumoea sect. Cyclocodon) were oblate sphaeroidal, semi-angular in polar outline, 3-colporate, with long colpi, long spinules, and thick nexine. Type III grains (found in all accessions of Codonopsis subg. Pseudocodonopsis) resembled Type I grains, but had the long spinules characteristic of Type II; further, the colpi were much shorter than in Type I and II. Type IV grains (found in all accessions of Codonopsis subg. Obconicicapsula) likewise resembled Type I grains, but had colpi of a length intermediate between Type I and Type m. The uniformity of pollen morphology in Campanumoea sect. Campanumoea, Codonopsis subgen. Codonopsis, and Leptocodon might be interpreted as supporting their merger as a single genus, while the distinctness of Type I and Type II pollen might be interpreted as supporting the recognition of Cyclocodon as a genus distinct from Codonopsis. However, the palynological data are less clear as to the disposition of Codonopsis subg. Pseudocodonopsis and subg. Obconicicapsula, and a realignment of generic boundaries must await completion of studies involving additional data sets.