This is an irregular feature - both in frequency and oddness - dedicated to a word I came across that I have never previously used.
hastate (HAS-tayt) a. (botany) possessing the shape of spear point but with the basal lobes pointing outward at right angles; shaped like a spear point with pointed lobes at the base.
I came across the term hastate in a horticultural book, and it might be easier to simply show a picture of a leaf with hastate features than to try to explain this shape:
Left: a leaf with a hastate shape
The term is Latin in origin, derived from the word hasta ("spear"). The use of the term hastate to describe leaf shapes probably owes something to the similarity in shape of the medieval battle weapon known as the halberd.