A developmental study on the cyathial nectaries in Euphorbia thymifolia L.

Four cyathial nectaries were found at the inside tip of the involucre in Euphorbia thymifolia L. The cyathial nectaries developed from a group of epidermal and hypodermal cells belonging to the involucre. Three regions could be distinguished in each nectary viz.: 1) a single layer of palisade-like epithetial cells, 2) one or two layers of stalk cells, and 3) basal parenchymatous cells. Starch grains and proteins were localized in the epithelial and stalk cells, but not in the basal cells. The enzymes, acid phosphatase and succinate dehydrogenase were also localized