The Spiny Pollen Wall in Sauromatum (Araceae)-with Special Reference to the Endexine

Pollen grains of Sauromatum are inaperturate with a microechinate exine ornamentation. The outer pollen wall is formed by the spongious endexine and spines. An acetolysis-resistant ektexine is missing. The endexine appears electron dense after TCH-Sp staining and electron translucent after the Thiéry-test. The spines are polysaccharidic in nature. Acetolysis leads to a considerable increase in pollen size and destroys the spines. PAS-positive Ubisch body-like structures are found within the anther loculus. The tapetum is of the amoeboid type. Spines as well as Ubisch bodylike structures are formed by the tapetum at the stage of first pollen mitosis