The monophyly of the Arbutoideae is also well supported in the combined analysis. The following morphological characters are likely synapomorphic for members of this clade: inside of corolla with unicellular hairs (char. #49), filaments conspicuously asymmetrically dilated (char. #54), indehiscent fruit (char. #78), fleshy fruits, brightly colored (char. #82), with a bony or fibrous endocarp (char. #81), and plants with high levels of ellagic acid (char. #86). Only the last is not homoplasious (but it has been insufficiently investigated). The others also occur in a few or several other groups within the Ericaceae. The presence of a bony or fibrous endocarp, however, occurs elsewhere only in Empetreae and in some Styphelioideae, although sclerids occur in the endocarp of the bony capsules of Craibiodendron. Although not coded in the analysis, the Arbutoideae may also be united by the reduction in the number of ovules per locule. In this clade the ovule number varies from few to one, whereas most Ericaceae have more or less numerous ovules per locule.
Arbutoideae (Meisn.) Nied., Bot. Jahrb. Syst. 11: 135. 1889. – Type genus: Arbutus L.
Arbuteae Meisn., Pl. Vasc. Gen.: Tab. Diagn. 243, Comm.
154. 1839.

Trees or shrubs, usually evergreen, usually alternate, non-ericoid, entire or serrate leaves, convolute in bud. Leaf epidermal cells not lignified. Indumentum of stalked glandular hairs and sometimes elongate, non-glandular hairs. Inflorescences terminal, racemose or paniculate; bracts present, bracteoles paired, ± basal; calyx not articulated with pedicel. Flowers (4-)5-merous, actinomorphic. Calyx lobes small, persistent; corolla sympetalous, urceolate, with long unicellular hairs on the inside, the lobes small; stamens (8-)10, included, the filaments ± strongly dilated basally, ± straight, unicellular-pubescent or smooth; anthers tetrasporangiate, inverting only just before anthesis, slightly roughened, with a pair of dorso-apical spurs, lacking a fibrous endothecium, lacking disintegration tissue, dehiscing by terminal pores or slit-like pores. Pollen in tetrads, without viscin threads. Ovary 4—10-locular, with axile placentation and only 1-few ovules per locule, superior, sometimes with fleshy papillae; style continuous with the ovary; stigma truncate. Fruit ± fleshy with bony or fibrous endocarp, i.e., a drupe or drupe-like berry; seeds with testa cells ± elongated; embryo with 2 cotyledons.

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