Neotropical Setchellanthaceae

Vinicius Castro Souza

Herbarium ESA - Escola Superior de Agricultura Luiz de Queiroz (ESALQ-USP), Brazil.

Description

Shrub; indumentum with T-shaped hairs.  Leaves spirally arranged, simple, without stipules.  Flowers axillary, solitary, actinomorphic, bisexual, showy; sepals (5-)6(-7), enclosing the flower bud, splitting irregularly at anthesis; petals (5-)6(-7), free, imbricate, clawed, blue to lilac; stamens many, centrifugal, disposed in 5-7 groups on an elongated axis, anthers bithecate, introrse, opening by longitudinal slits; nectary absent; ovary syncarpous with 3 carpels, 3-locular, with a short gynophore, ovules 10-14 per carpel, with axile placentation, style short.  Fruits elongate septifragal capsules.

Notes on delimitation

  • Setchellanthaceae is a monotypic family, recently described (Iltis, 1999), previously included in Capparaceae, includes the species Setchellanthus caeruleus Brandegee.
  • The family belong to Brassicales, as a sister group to a large clade, which includes most of families of this order (APG III, Hernández-Hernández et al. 2013).

Distribution in the Neotropics

  • The family is endemic to Mexican desert, only in the Chihuahuan Desert and in the Tehuacán-Cuicatlán Valley.

Distinguishing characters (always present)

  • Indumentum with T-shaped hairs.
  • Leaves spirally arranged, simple, without stipules.
  • Flowers axillary, solitary.
  • Sepals closed in bud, splitting irregularly at anthesis.
  • Stamens many, disposed in 5-7 groups on an elongated axis.

Other important characters

  • Xeromorphic shrubs.
  • Smelling odour.

Key differences from similar families

  • The Setchellanthus was previously included in Capparaceae which is polymorphic family distinguished from Setchellanthaceae especially by the sepals and petals usually 4 (vs. (5-)6(-7)) and carpels usually 2 (vs. 3).

Number of genera

  • One: Setchellanthus Brandegee

Status

  • The family is endemic to Mexican desert, only in the Chihuahuan Desert and in the Tehuacán-Cuicatlán Valley.

Important literature

Hernández-Hernández, T., Colorado, W.B. & Sosa, V. 2013.  Molecular evidence for the origin and evolutionary history of the rare American desert monotypic family Setchellathaceae.  Org. Divers. Evol. DOI 10.1007/s13127-013-0136-4.

Iltis, H.H. 1999.  Setchellanthaceae (Capparales), a New Family for a Relictual, Glucosinolate-Producing Endemic of the Mexican Deserts. Taxon 48(2): 257-275.

Kubitzki, K. 2002. Setchellanthaceae. In K. Kubitzki, & C. Bayer (eds.). The Families and Genera of Vascular Plants, V: Dicotyledons; Malvales, Capparales, and non-betalain Caryophyllales, pp. 353-354. Springer-Verlag, Berlin.

How to cite

Souza, V.C. (2013). Neotropical Setchellanthaceae. 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/Setchellanthaceae.htm.