Neotropical Samolaceae

Description

Herbs sometimes with a woody base, rarely sub-shrubs, indumentum of stalked or sessile glandular hairs occasionally present, secretory cavities appear as red or brownish lines on inflorescence or as dots or uneven lines on calyx and bracts. Leaves in a basal rosette, sometimes with leaves alternate and spiraling up stem, simple, entire, leaf margins entire venation pinnate, petiolate, can appear sessile due to decurrent margins. Inflorescences terminal racemes, corymbs or panicles, single bract present at base or in middle of pedicel or ebracteate. Flowers bisexual, pentamerous, actinomorphic, calyx tube adnate to ovary, persistent in fruit, corolla aestivation imbricate, connate into a tube, lobes broadly ovate; stamens 5, adnate to corolla, oppositipetalous; anthers dehiscing via longitudinal slits; staminodes 5, regularly present, adnate to corolla, alternipetalous; ovary mostly inferior, syncarpous, carpels 5, unilocular, ovules many, style 1. Fruit dry, spherical, capsular, dehiscing loculicidally via 5 valves. Seeds numerous, small, angular, brownish.

Notes on delimitation

• Samolaceae is a monogeneric family within the order Ericales and is sister to Theophrastaceae (Stahl 2004) - in which it is often included.
• If not found within Theophrastaceae then try Primulaceae where Samolus L. is generally placed in its own tribe, the Samoleae (Kallersjo et al. 2000).

Distribution in the Neotropics

• Approximately 12 species found with a cosmopolitan distribution.
• Especially prevalent around salt-marshes.
• C. 2 species found throughout the Neotropics.

Distinguishing characters (always present)

• Semi-inferior ovary; formed from an incompletely formed hypanthium (Kallersjo et al. 2000).
• Capsular fruit.
• Terminal inflorescence.
• Flower parts in sets of 5.
• Bisexual, actinomorphic flowers.
• Petals fused to form a corolla tube.
• Stamens 5 and opposite and adnate to the petals.
• Carpels 5.
• Style 1 (forming the superior part of the ovary).

Other important characters

• Pubescent.
• Floral parts with red or brown streaks or spots.
• Leaves alternating up the stem but primarily in a basal rosette.
• Leaves petiolate but can look as if sessile.
• Single bract present at the base of, or midway along, the peduncle.
• White corolla, sometimes pink or purple.
• 5 staminodes alternating with and connected to the opening of the corolla tube.
• Calyx persistent in fruit.
• Fruit globose opening by 5 valves.
• Numerous seeds.

Key differences from similar families

Differs from Theophrastaceae in having:

• Dry fruits.
• A partly inferior ovary.
• Small angular seeds.

Differs from Primulaceae in having:

• A partly inferior ovary.

Number of genera

• One: Samolus.

Status

• Native.

Important literature

Brummitt, R.K. 2007.  Heywood, V.H., Brummitt, R.K., Culham, A. and Seberg, O. (eds.). Flowering Plant Families of the World, p. 219. Royal Botanic Gardens, Kew.

Caris, P.L. and Smets, E.F. 2004.  A floral onogenetic study on the sister group relationship between the genus Samolus (Primulaceae) and the Theophrastaceae. American Journal of Botany 91(5): 627-643.

Kallersjo, M. Bergqvist, G. and Anderberg, A. 2000.  Generic realignment in Primuloid families of the Ericales s.l. A phylogenetic analysis based on DNA sequences from three chloroplast genes and morphology. American Journal of Botany 87(9): 1325-1341.

Maas, P.J.M. and Westra, L.Y. Th. 2005.  Neotropical Plant Families. 3rd ed., p. 249. A.R.G. Gantner Verlag K.G., Ruggell.

Ståhl, B. 2004.  Samolaceae. In: Kubitzki, K. (ed.), Families and genera of vascular plants vol. 6. pp. 387-389. Springer-Verlag, Berlin.

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

How to cite

Every, J.L.R. (2009). Neotropical Samolaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Samolaceae.htm.