The family Malvaceae (sensu stricto) comprises ca. 111 genera and 1800 species (but Mabberley 2017 broader circumscription of the family, and cites 229 genera and 5100 species, while Christenhusz 2017 cites 244/4225) of herbs, shrubs, or small trees pantropical and subtropical in distribution, sometimes extending into temperate areas.  Based on recent DNA analysis, APG IV, Christenhusz (2017), and Mabberley (2017) have moved the families Sterculiaceae, Bombacaceae, and Tiliaceae into the Malvaceae, but the traditional assignment in separate families is retained here.  Seven genera comprising ten species occur in Samoa—one endemic, four indigenous, and the rest are Polynesian or modern introductions. 

Key to Malvaceae Genera of Samoa

 

1. Corolla yellow with a purple base; trees or shrubs

   2. Capsule splitting open at the tip; tree or shrub; corolla lemon-yellow …………...… Hibiscus

   2. Capsule globose, non-splitting; common littoral tree; corolla pale yellow ………...Thespesia

1. Corolla white, pink, or pale orange; shrubs, subshrubs, or rarely trees

   3. Seeds covered with cotton hairs; corolla white; rare littoral shrub …...…………. Gossypium

   3. Seeds glabrous, not cottony; corolla pink or pale orange, or if white, then a tree

      4. Plant an uncommon tree of montane to cloud forest tree; corolla white …..……... Abutilon

      4. Plant a weedy shrub or subshrub, corolla pale orange or pink

         5. Staminal column bent downward; flowers pink; fruit a bur …………………….... Urena

         5. Staminal column straight; flowers pale orange; fruit a splitting schizocarp

            6. Epicalyx of 3 bracts subtending the calyx; rare weedy species …….….…. Malvastrum

            6. Epicalyx lacking; common weedy species …….……………………….……….… Sida