Neotropical Theaceae

Description

Trees (up to 20m) or shrubs, usually evergreen, indumentum of unicellular trichomes or glabrous. Leaves spiral or distichous, simple, petiolate or sessile (appearing petiolate due to the decurrent base), often asymmetric, coriaceous, margins serrate (rarely entire), with small deciduous bristle-like glands terminating each tooth, venation pinnate more or less craspedromous or obscure (Laplacea Kunth), exstipulate. Flowers solitary (occasionally appearing fasciculate or racemose (Camellia L.), axillary, hermaphroditic (in Camellia) or unisexual (Laplacea), sepaloid, 2 prophylls or 2-7 involucral bracteoles intergrading with the calyx and corolla making the perianth parts indistinguishable from one another; calyx with 5-6 or rarely more sepals, these imbricate, basally connate or distinct, often persistent in fruit; corolla with 5-6 (-10) petals, these imbricate, distinct or slightly basally connate; stamens 20-40, free or rarely basally to fully connate, frequently adnate to base of corolla, centrifugal, with 5 primordia opposite each petal or with ring primordium in 2-5 whorls, anthers articulated, versatile or dorsifixed, opening by longitudinal slits, staminodia present in female flowers; gynoecium (3-)5(-10), syncarpous, ovary superior, occasionally hirsute, 3-5-loculate, styles 1, lobed or 3-5, capitate. Fruit a spheroidal, woody, loculicidal capsule c. 2 cm long, generally with a persistent calyx, columella persistent. Seeds few, 0.4-2cm long, flattened, oblong apical wings present or not (Camellia).

Notes on delimitation

• Theaceae s.s. is made up of ca. nine genera and up to 460 species with a centre of diversity in the subtropics and tropics, predominately in Southeast Asia (Prince 2007). The family has been greatly reduced over the years and has previously contained four subfamilies, 40 genera and ca. 600 species.
• A former subfamily Ternstroemioideae sensu Cronquist is treated as a separate entity within the Pentaphylacaceae in Neotropikey.
• Analyses of rbcL sequence data and morphological features show that Theaceae s.l. does not form a natural family (APG 2002) and is treated here in the same way as the subfamily Theoideae sensu Cronquist containing the Neotropical Laplacea and the cultivated Camellia.
• Theaceae s.s. is regarded as paraphyletic with Ternstroemiaceae (Morton 1996).
• Laplacea has long been synonymised with the Neotropical Gordonia J. Ellis, but is recognised as a distinct genus following phylogenetic work (Prince and Parks 2001).

Distribution in the Neotropics

• Laplacea Kunth can be found throughout the Neotropics growing mainly in cloud forests at altitudes of between 1,900-2,500m. Thought to have approximately 3-8 species. 
• Camellia sinensis (L.) Kuntze is widely cultivated as a tea plant, particularly in Cuzco, Peru.
• Camellia japonica L. is grown in gardens for its flowers which possess great ornamental value. This genus has its centre of distribution in Southeast Asia.

Distinguishing characters (always present)

• Trees or shrubs.
• Thick and serrate exstipulate leaves (regularly turning red before dropping).
• Tiny theoid gland at the tip of each tooth of the laminar margin.
• Imbricated perianth segments (quincuncical).
• Capsular fruit with a persistent central, woody axis (columella).

Other important characters

• Showy flowers (fragrant in Camellia).
• The bracteoles, calyx and corolla are quite often arranged spirally and are frequently impossible to tell apart.
• Corolla connate at base.
• Numerous stamens.
• Stamens adnate to base of corolla.
• Ovary hirsute.
• Flattened seed (winged in Laplacea).

Key differences from similar families

The Theaceae share a number of similarities with the following families but, these families differ in having the features listed below:

• Bonnetiaceae - white to yellow exudate.
• Kielmeyeroideae of the Clusiaceae - exudate present.
• Sapotaceae - exudate present.
• Actinidiaceae - inflorescence a thyrse, fruit a berry with numerous seeds.
• Pentaphylacaceae - fruit baccate, black gland dots on the underside of  the leaf.
• Tetrameristaceae - fruit a berry, racemose inflorescence.
• Symplocaceae - densely pubescent, fruit a drupe, inferior ovary.

Number of genera

• Two genera: Lapacea (native) and Camellia (introduced).

Notable genera and distinguishing features

Laplacea:

• Trees.
• Asymmetrical lamina.
• Bracteoles deciduous.
• Unisexual flowers.
• Ovary (3-)5(-10)-locular.
• Stigmas capitate.
• Winged seed.

Camellia:

• Shrubs or trees up to 9 m high.
• Petiole 3-10mm long.
• Apparently racemose or fasciculate inflorescence.
• Bracteoles 2 or more, not sharply differentiated from calyx.
• Ovary 3(-5) locular.

Status

• Laplacea is a native genus and Camellia introduced.

Important literature

Airy-Shaw, H. K. 1936.  Notes on the genus Schima and on the classification of the Theaceae-Camellioïdeae. Bulletin of Miscellaneous Information (Royal Gardens, Kew) 9: 496-499.

Culham, A. 2007.  Theaceae. In:  Heywood, V.H., Brummitt, R.K., Culham, A. and Seberg, O. (eds.). Flowering Plant Families of the World, p. 318. Royal Botanic Gardens, Kew.

Kobuski, C. 1950.  Studies in the Theaceae, XX. Notes on the South and Central American species of Laplacea and Gordonia (Theaceae). J. Arnold Arbor. 31: 405-429.

Luna, I. and Ochoterena, H. 2004.  Phylogenetic relationships of the genera of Theaceae based on morphology. Cladistics 20: 223-270.

Maas, P.J.M. & Westra, L.Y. Th. 2005.  Neotropical Plant Families. 3rd ed, p. 248. A.R.G. Gantner Verlag K.G., Ruggell.

Morton, C. M., Chase, M. C., Kron, K.A. and Swensen, S.M. 1996.  A molecular evaluation of the monophyly of the order Ebenales based upon rbcL sequence data. Syst. Bot. 21: 567-67.

Pennington, T.D. 2004.  Illustrated guide to the trees of Peru, Pp. 212-215. David Hunt Press, Milborne Port Sherborne.

Pool, A. 2001.  Theaceae. Pp. 2443-2448. In: W.D. Stevens, C. Ulloa Ulloa, A. Pool and O. M. Montiel (eds.), Flora de Nicaragua vol. 3, Angiosperms (Pandanaceae-Zygophyllaceae). Missouri Botanical Garden Press, St. Louis.

Prince, L. M. 2007.  A brief nomenclatural review of genera and tribes in Theaceae. Aliso 24: 105-121.

Prince, L. M. and Parks, C. L. 2001.  Phylogenetic relationships of Theaceae inferred from chloroplast DNA sequence data. American Journal of Botany 88(12): 2309-2320.

Sealy, J. R. 1958.  A revision of the genus Camellia. The Royal Horticultural Society, London.

Stevens, P.F. 2008.  Angiosperm Phylogeny Website. Version 9 onwards. http://www.mobot.org/MOBOT/research/APweb/.

Stevens, P.F., Dressler, S. and Weitzman, A.L. 2004a.  Theaceae. Pp. 463-471. In: Kubitzki, K. (ed.), Families and Genera of Vascular Plants vol. 6. Springer-Verlag, Berlin, Heidelberg, New York.

Stevenson, D.W. and Stevenson, J.W. 2004.  Theaceae. Pp. 369-370. In: Smith, N., Mori, S.A., Henderson, A., Stevenson, D.W. and Heald, S.V. (eds.). Flowering Plants of the Neotropics. The New York Botanical Garden, Princeton University Press, Princeton.

Watson, L. and Dallwitz, M.J. (1992 onwards).  The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version 25th November 2008. http://delta-intkey.com.