Definition from Wiktionary, the free dictionary
acalymmate (not comparable)
- (palynology) Forming clusters of pollen grains (usually tetrads or polyads) in which the sexines of the respective grains do not merge to form a continuous sheath.
1996, John V. Freudenstein & Finn N. Rasmussen, “Sectile Pollinia and Relationships in the Orchideaceae”, Plant Systematics and Evolution, volume 205, DOI:10.1007/BF01464400, pages 125-146:
- When loosely associated, each tetrad retains most of its outer exine layer, leading to calymmate tetrads, but an acalymmate massula (since the exine is not continuous around each massula […] ).