Neotropical Podostemaceae

*Claudia Petean Bove and **C. Thomas Philbrick

*Museu Nacional da Universidade Federal do Rio de Janeiro, Brazil.
**Western Connecticut State University, USA.

Description

Annual or perennial herbs, firmly attached to rocks and other solid substrates in seasonally strong currents of rivers and streams. Roots linear, prostrate and flattened, green, branched or not, or roots lacking. Stems prostrate, tightly attached to substrate throughout its length or arising along flanks of roots, opposite or sub-opposite, disk-shaped (holdfast-like) or upright. Leaves distichous or tristichous, arising from stem margins, or projecting from an upright stem, petiolate or sessile; petioles terete to flattened, sometimes winged, mono- or dithecous; blades variable, simple, lobed, repeatedly pinnately or dichotomously compound; when divided, ultimate divisions hair-like or flattened, blunt or acute at apex. Flowers bisexual, solitary, fascicled or in 2-sided spiciform monochasia, pedunculate or not; actinomorphic or zygomorphic; enclosed in  sac-like spathella or spathella lacking; tepals 0-20, in complete or incomplete whorl, free or fused basally, linear, lanceolate or triangular; stamens 1-40, free or fused basally, in 1-2 complete whorls, or confined to one side of flower, or borne at apex of andropodium; filaments elongating during anthesis (most common) or not, anthers basifixed, dehiscing introrsely,  latrorsely or extorsely; pollen in monads, dyads or tetrads, tricolporate, tricolpate or pantopate; ovary 2-3-carpellate superior, sometimes borne on a short gynophore  at anthesis; placenta fleshy, axillary; ovules axile, anatropous, bitegmic, tenuinucellate; stigmas 1-2-3, free or fused basally. Fruits capsular, 1-3-locular, 2-3-valved, septifragal longitudinally, smooth, ribbed or keeled, equal or unequal valves, both valves persistent or one deciduous; suture margins thickened or not; pedicel elongating (most common) in fruit or not; seeds ca. 1-2 mm long, numerous, becoming sticky upon wetting, without endosperm; embryo straight.

Notes on delimitation

  • Historically the family was placed in the monotypic order Podostemales by Engler (1964), Cronquist (1981) and Takhtajan (1969). In the first version of the classification of the angiosperms given by the Angiosperm Phylogeny Group (1998), the family was left apart in an uncertain position. In the second version (APG II, 2003) Podostemaceae was assigned to Malpighiales related to Clusiaceae and Bonnetiaceae. In the latest version (APG III, 2009) a close relationship with Hypericaceae (formerly a part of Clusiaceae) was confirmed.

Distribution in the Neotropics

  • Worldwide Podostemaceae comprise ca. 50 genera and approximately 270 species. About 20 genera and 150 species occur in the Neotropics. The family is pantropical with a few species extending into temperate eastern Asia and eastern North America. In the Neotropics it ranges from central Mexico to northern Paraguay and Argentina.

  • Apinagia Tul. - about 50 species, Colombia to Paraguay and Uruguay, mainly in Guiana and Brazil Shields.
  • Castelnavia Tul. & Wedd. - six species, central and southeastern Brazil to eastern Bolivia.
  • Ceratolacis (Tul.) Wedd. - two species, endemic to central Brazil.
  • Cipoia C.T.Philbrick, Novelo & Irgang - two species, endemic to southeastern Brazil.
  • Diamantina Novelo, C.T. Philbrick & Irgang - monospecific (D. lombardii Novelo, C.T. Philbrick & Irgang), endemic to southeastern Brazil.
  • Jenmaniella Engl. - seven species in Guiana and Brazil Shields.
  • Lonchostephus Tul. - monospecific (L. elegans Tul.), endemic to southeastern Brazil.
  • Lophogyne Tul. - monospecific (formerly two species, recently put in synonymy (Bove et al. 2010), endemic to central Brazil.
  • Macarenia P. Royen - monospecific (M. clavigera P. Royen), endemic to Colombia.
  • Marathrum Humb. & Bonpl. - nine species, West Indies and southern Mexico through Central America to South America (Brazil, Guiana Shield, southern Paraguay and northern Argentina).
  • Monostylis Tul. - monospecific (M. capillacea Tul.) endemic to central Brazil.
  • Mourera Aubl. - six species, Colombia through Guiana Shield to Brazil, Paraguay and northern Argentina.
  • Oserya Tul. & Wedd. - seven species, west-central Mexico, Venezuela, Guianas and northern Brazil.  Recent phylogenetic studies indicate the genus is not monophyletic (Tippery et al., pers. comm.).
  • Podostemum Michx. - 11 species, eastern North America, central Mexico, Colombia, southeastern South America (Argentina, Brazil, Paraguay, Uruguay).
  • Rhyncholacis Tul. - 22 species, northern South America.
  • Tristicha Touars - one polymorphic species (T. trifaria (Bory ex Willd.) Spreng.), widely distributed in tropical and subtropical America, Africa and Asia.
  • Tulasneantha P.Royen - monospecific (T. monoadelpha (Bong.) P. Royen), endemic to central Brazil.
  • Vanroyenella - monospecific (V. plumosa Novelo & C.T. Philbrick).  Phylogenetic analyses (Tippery et al., pers. comm.) support transfer of V. plumosa into Marathrum.
  • Weddellina (Warm.) Engl. - monospecific (W. squamulosa Tul.), northern South America (Guianas, Venezuela) and central Brazil.
  • Wettsteiniola Suess. - three species, southern Brazil to northern Argentina and Paraguay.

Distinguishing characters (always present)

  • Plants grow attached tightly to rocks or other solid substrates in strong currents of river-rapids and waterfalls, usually in sunny places.
  • Flowering and seed production occur when plants become exposed during seasonally low water levels.

Other important characters

  • Remarkably variable in form.  Some lichen- or algae-like in overall appearance.
  • Presence of a sac-like cover (spathella) that encloses the young flower (absent in Tristicha and Weddellina).

Key differences from similar families

  • There are no similar families in the Neotropics.

Number of genera

There are twenty genera in the Neotropics (see above).

Useful tips for generic identification

  • Apinagia and Marathrum are difficult to distinguish. Apinagia has some species with prostrate stems while Marathrum has all species with prostrate stems. Both genera are polyphyletic (Tippery et al., pers. comm.).
  • Castelnavia - when exposed in the air it looks like a lichen (a white spot in the rock), ovary surrounded by stem tissue during and after anthesis, asymmetrically inflated pedicel apex, anisolobous ovary perpendicular to pedicel axis, unilocular mature capsule, and one deciduous capsule valve.
  • Ceratolacis - presence of andropodium, stigma triangular becoming hardened and persisting in fruit, capsule slightly flattened.
  • Cipoia - presence of gynophore at anthesis, ovary enclosed within ruptured spathella during and after anthesis, capsule enclosed by ruptured spathella, single stamen per flower.
  • Diamantina - digitate leaves, gynophore at anthesis.
  • Jenmaniella - presence of a gynophore at anthesis.
  • Lonchostephus  - stamen filaments distinctly widened and flat.
  • Lophogyne - flattened, irregularly dentate stigmas.
  • Macarenia  - many flowers inside spathella.
  • Monostylis - presence of a gynophore at anthesis, capsules elongate and flattened, each capsule valve with 5 non-suture ribs per valve.
  • Mourera - rough leaves, often with showy two sided spike-like monochasial inflorescence.
  • Oserya - South American species with prostrate stem, 3 tepals per flower, 5 non-suture ribs per capsule valve; Mexican species with upright stem, 2 tepals per flower, 5 non-suture ribs per capsule valve.
  • Podostemum - distinct stipules persistent on old stems, pollen in dyads, presence of andropodium.
  • Rhyncholacis - flowers in fascicles arising from prostrate stem, flattened capsules with midrib extensions on both sides that are contiguous with the persistent rigid styles.
  • Tulasneantha - stamen filaments united for half their length forming an androecial tube.
  • Tristicha - moss-like appearance, tristichous leaves, trimerous flower and fruit.
  • Vanroyenella - plumose leaves, indurate stamen filaments.
  • Weddellina - flowering stems short (< 2 cm) and unbranched, vegetative stems to ca. 1 m long and branched, vegetative stems with reduced scale-like leaves, spathella lacking, style one, stigma globose.
  • Wettsteiniola - flowers in fascicles, fruits with 5 ribs per valve.

Notable genera and distinguishing features

  • See above.

Status

  • Only native taxa are found.

Important literature

Bove, C.P., Philbrick, C.T. and Costa, J.E.M. 2010 (in press). Distribution and emended description of the Neotropical Podostemacean genus Lophogyne. Brittonia.

Cook, C.D.K. and R. Rutishauser.  2007. Podostemaceae, pp. 304-344.  In: Kubitzki, K. (ed.), The Families and Genera of Vascular Plants vol. 9. Springer-Verlag, Berlin.

Philbrick, C.T., Bove, C.P. and Edson, T.C. 2009. Monograph of Castelnavia (Podostemaceae). Systematic Botany 34(4): 715-729.

Philbrick, C.T., Bove, C.P. and Stevens, H.I. 2010. (in press). Endemism in neotropical Podostemaceae. Annals of the Missouri Botanical Garden.

Philbrick, C.T.  and Novelo R., A. 2004. Monograph of Podostemum (Podostemaceae). Systematic Botany Monographs 70: 1-106.

Philbrick, C.T., Novelo R., A. and Irgang, B.E. 2004. Two new genera of Podostemaceae from the state of Minas Gerais, Brazil.  Systematic Botany 29: 109-117.

Royen, P. van. 1951. The Podostemaceae of the New World. Part I. Meded. Bot. Mus. Herb. Rijks. Univ. Utrecht 107: 1-151.

Royen, P. van. 1953. The Podostemaceae of the New World. Part II. Acta Botanica Neerlandica 2(1): 1-20.

Royen, P. van. 1954. The Podostemaceae of the New World. Part III. Acta Botanica Neerlandica 3: 215-263.

How to cite

Bove, C.P. & Philbrick, C.T. (2010). Neotropical Podostemaceae. 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/Podostemaceae.htm.

Click images to enlarge


Habit of Apinagia longifolia © C.P. Bove, Museu Nacional (UFRJ).



Leaves and flowers of Apinagia longifolia © C.P. Bove, Museu Nacional (UFRJ).



Capsules of Apinagia longifolia © C.P. Bove, Museu Nacional (UFRJ).



Apinagia longifolia © C.P. Bove, Museu Nacional (UFRJ).



Flowes of Castelnavia princeps © C.P. Bove, Museu Nacional (UFRJ).



Fruits of Castelnavia princeps © C.P. Bove, Museu Nacional (UFRJ).



Habit of Lonchostephus elegans © C.P. Bove, Museu Nacional (UFRJ).



Inflorescence of Lonchostephus elegans © C.P. Bove, Museu Nacional (UFRJ).



Habit of Lophogyne arculifera © C.P. Bove, Museu Nacional (UFRJ).



Flower of Lophogyne arculifera © C.P. Bove, Museu Nacional (UFRJ).



Stem, leaves and buds of Marathrum capillaceum © A. Oliveira, Museu Nacional (UFRJ)



Stem, leaves and buds of  Marathrum capillaceum © A. Oliveira, Museu Nacional (UFRJ)



Flowers of Marathrum capillaceum © A. Oliveira, Museu Nacional (UFRJ)



Fruits of Marathrum capillaceum © C.P. Bove, Museu Nacional (UFRJ).



Leaves of Monostylis capillacea © C.P. Bove, Museu Nacional (UFRJ).



Flowers of Monostylis capillacea © C.P. Bove, Museu Nacional (UFRJ).



Fruits of Monostylis capillacea © C.P. Bove, Museu Nacional (UFRJ).



Seed germination of Mourera aspera © C.P. Bove, Museu Nacional (UFRJ).



Habit of Mourera aspera © C.P. Bove, Museu Nacional (UFRJ).



Habit of Podostemum ovatum © C.P. Bove, Museu Nacional (UFRJ).



Habit of Podostemum weddellianum © C.P. Bove, Museu Nacional (UFRJ).



Habit of Rhyncholacis linearis © C.P. Bove, Museu Nacional (UFRJ).



Habit of Tristicha trifaria © C.P. Bove, Museu Nacional (UFRJ).



Capsules of Tristicha trifaria © C.P. Bove, Museu Nacional (UFRJ).



Habit of Weddellina squamulosa © C.P. Bove, Museu Nacional (UFRJ).



Flowers of Weddellina squamulosa © C.P. Bove, Museu Nacional (UFRJ).