Another interesting platform for kin vs. group selection is family Pyrolaceae (see Hideki Takahashi (1986) Pollen polyads and their variation in chimaphila (pyrolaceae), Grana, 25:3, 161-169) .

Without going into too much detail, it has about 4 genera; of them, Chimaphila has pollen organized into groups of about a hundred grains! It means that when the polyad (that's what the clump is called) lands on a stigma, multiple ovules (females) will get sperm (males) from the same father, and the resulting offspring should be much closer genetically than if multiple fathers contributed in equal measures. (My intuition is that fertilization is not frequent in these plants, though I have seen the fruits.) That is definite evidence for kin selection, isn't it? However, why is it not more widespread? "Three other generain the Pyrolaceae, Orthilia , Pyrola, and Moneses, have flowers with numerous ovules like that of Chimaphila, but the first of these produces pollen monads and the two others pollen tetrads." Also, [I think that] at least in Ukraine Orthilia and Pyrola are more common than Chimaphila (which is, even if actually true, only anecdotal evidence considering the total ranges of the genera.) (Another problem is that all those plants need fungal symbionts, and there's little data on their diversity.) What differencies in seed quality & dispersion, and population strategies would kin selection predict for Chimaphila and (Pyrola and Orthilia)?