Rotheca is a genus of flowering plants in the family Lamiaceae. Estimates of the number of species in the genus vary from about 35  to as many as 60. Three of the species are native to tropical Asia, with the rest occurring in Sub-Saharan Africa. The type species for the genus is Rotheca serrata. It had originally been named Rotheca ternifolia, but this name is now considered illegitimate.
In the 20th century, Rotheca was rarely recognized as separate from Clerodendrum. Rotheca was revived in 1998 as a result of phylogenetic analysis of DNA sequences. It can easily be distinguished from Clerodendrum by a combination of morphological characters.
Rotheca is a genus of shrubs, subshrubs, and perennial herbs, with a few becoming lianas or small trees. They emit an unpleasant odor when damaged. The leaves are opposite or whorled, and sessile or with a short petiole. The calyx is actinomorphic or nearly so, and not accrescent as in some related genera. The corolla is blue, purple, or white, (rarely yellow), and 5-lobed. The abaxial lobe is often larger and different in color. The four stamens are long-exserted. The ovary is unlobed at anthesis, becoming lobed during maturity. The fruit is 4-lobed and resembles a drupe, but eventually separates into four 1-seeded mericarps.
In 1895, John Isaac Briquet included Rotheca in his rather broad circumscription of Clerodendrum. Briquet's treatment was generally followed for the next 100 years, but doubts about it were often expressed. The genus Rotheca was revived in 1998, based on molecular phylogenetic work, some of which was not published until 1999. In this work, it was shown that inclusion of Rotheca in Clerodendrum renders the latter polyphyletic.
One commonly consulted species list provides only a few examples. The transfer of species from Clerodendrum to Rotheca continues in a piecemeal fashion, and is mostly for the compilation of local floras.
- Rotheca incisa (Klotzsch) Steane & Mabb.
- Rotheca myricoides (Hochst.) Steane & Mabb. (syn. Clerodendrum ugandense) Prain – Butterfly Bush
- Rotheca serrata (L.) Steane & Mabb.
- Raymond M. Harley, Sandy Atkins, Andrey L. Budantsev, Philip D. Cantino, Barry J. Conn, Renée J. Grayer, Madeline M. Harley, Rogier P.J. de Kok, Tatyana V. Krestovskaja, Ramón Morales, Alan J. Paton, and P. Olof Ryding. 2004. "Labiatae" pages 167-275. In: Klaus Kubitzki (editor) and Joachim W. Kadereit (volume editor). The Families and Genera of Vascular Plants volume VII. Springer-Verlag: Berlin; Heidelberg, Germany. ISBN 978-3-540-40593-1
- David J. Mabberley. 2008. Mabberley's Plant-Book third edition (2008). Cambridge University Press: UK. ISBN 978-0-521-82071-4
- Dorothy A. Steane and David J. Mabberley. 1998. "Rotheca (Lamiaceae) Revived". Novon 8(2):204-206.
- George W. Staples and Derral R. Herbst "A Tropical Garden Flora" Bishop Museum Press: Honolulu (2005)
- Constantine S. Rafinesque. 1838. Flora Telluriana 4:69. (see External links below).
- John Isaac Briquet. 1895. "Clerodendrum" pages 174-176. In: "Verbenaceae" pages 132-182. In: Die Natürlichen Pflanzenfamilien volume IV, part 3a. Verlag von Wilhelm Engelmann: Leipzig, Germany.
- Yao-Wu Yuan, David J. Mabberley, Dorothy A. Steane, and Richard G. Olmstead. 2010. "Further disintegration and redefinition of Clerodendrum (Lamiaceae): Implications for the understanding of the evolution of an intriguing breeding strategy". Taxon 59(1):125-133.
- Dorothy A. Steane, Robert W. Scotland, David J. Mabberley, and Richard G. Olmstead. 1999. "Molecular systematics of Clerodendrum (Lamiaceae): ITS sequences and total evidence". American Journal of Botany 86(1):98-107.
- Species of Rotheca. At: Rotheca. At: Lamiaceae. At: Queries. At: GRIN Taxonomy for Plants. (see External links below).
- Rosette B. Fernandes and Bernard Verdcourt. 2000. "Rotheca (Labiatae) revived - more new combinations". Kew Bulletin 55(1):147-154.
- Rotheca In: Flora Telluriana At: Biodiversity Heritage Library
- Rotheca Species At: Rotheca At: List of Genera At: Lamiaceae At: Family List At: Families and Genera in GRIN At: Queries At: GRIN Taxonomy for Plants
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