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 Thiery-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 body-like structures are formed by the tapetum at the stage of first pollen mitosis.