13d. Malvaceae Jussieu subfam. Grewioideae Dippel, Handb. Laubholzk. 3: 56. 1893. (as Grewieae).
Margaret M. Hanes
Herbs, subshrubs, or shrubs [trees]. Leaf blades usually unlobed, margins crenate to dentate. Inflorescences axillary, terminal, or leaf-opposed, fasciculate or cymose or solitary flowers. Flowers bisexual [plants rarely gynodioecious]; epicalyx absent; sepals usually persistent, 4 or 5, distinct, not petaloid, appendaged near apex [not appendaged]; petals (0–)4 or 5, distinct, base sometimes clawed, base with or without nectaries; androgynophore present or absent, base with or without nectaries; stamens [4–]5–100, distinct; anthers 2-thecate; staminodes absent [outermost stamen sometimes sterile]; gynoecium syncarpous. Fruits capsules, dehiscence loculicidal. Seeds 2–150, glabrous.
Genera 25, species ca. 700 (2 genera, 8 species in the flora): United States, Mexico, West Indies, Central America, South America, Asia, Africa, Indian Ocean Islands, Pacific Islands, Australia; mostly tropical.
A large portion of former Tiliaceae is now included in Grewioideae; the remaining members of the former Tiliaceae have been transferred to other subfamilies in Malvaceae or to other families (C. Bayer et al. 1999). Grewioideae are sister to Byttnerioideae; together they represent the earliest branching subfamilies in the family (Bayer et al.; R. Nyffeler et al. 2005). Relationships within the morphologically diverse Grewioideae have been difficult to resolve (Bayer et al.; W. S. Alverson et al. 1999). U. Brunken and A. N. Muellner (2012) provided a new tribal classification for Grewioideae and evidence that morphological characters traditionally used to delimit taxonomic groups in Grewioideae (for example, the presence of an androgynophore) have arisen multiple times independently and should not be used as synapomorphies to define groups.
SELECTED REFERENCE Brunken, U. and A. N. Muellner. 2012. A new tribal classification of Grewioideae (Malvaceae) based on morphological and molecular phylogenetic evidence. Syst. Bot. 37: 699–711.