Endosperm of Areca /betel nut is
The Areca is hard, but can be cut with a knife, and then exhibits a marbled interior (ruminate endosperm), dark brown lines alternating with opal-white portions. Ruminate endosperm in the Palms (Arecaceae). It is the condition in which the endosperm is dissected by in-growths of the seed coat, is a common condition in the palms. So, the correct answer is 'Ruminate'.