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  • Podostemaceae Rich. ex Kunth

This family is accepted.
PODOSTEMACEAE

[FWTA]

Podostemaceae, G. Taylor. Flora of West Tropical Africa 1:1. 1954

Morphology General Habit
Plant-body often reduced to a thallus usually attached to the substratum by haptera Shoots (when present) arising from a thalloid base and bearing simple or deeply divided, alternate, exstipulate or minutely stipulate leaves Aquatic herbs of rocks or stones in swift-flowing water or spray of waterfalls
Morphology Reproductive morphology Flowers
Flowers solitary or cymose, bracteate, hypogynous, zygomorphic
Morphology Reproductive morphology Flowers Perianth
Perianth 3-phyllous or rudimentary and then usually of 2 minute more or less subulate tepals in which case the flower is enclosed (and often inverted) within a spathaceous bract (spathella) which ruptures irregularly on emergence of the flower
Morphology Reproductive morphology Flowers Androecium
Stamens 1–2 (rarely 3 or 4), filaments free or connate at the base; anthers 4-locular, opening lengthwise; staminode inserted between 2 stamens in Stonesia; pollen-grains solitary or geminate
Morphology Reproductive morphology Flowers Gynoecium
Ovary sessile or shortly stipitate, of 2–3 united carpels, 1–3-locular; stigmas 1–3; ovules numerous on axile placentas
Morphology Reproductive morphology Fruits
Fruit a septicidal capsule
Morphology Reproductive morphology Seeds
Seeds minute, exalbuminous

[NTK]

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

Morphology
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.

General Description
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.
Number of genera

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

Status
  • Only native taxa are found.
Distribution
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.
Diagnostic
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.
Key differences from similar families
  • There are no similar families in the Neotropics.
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).
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 pedicelapex, anisolobous ovary perpendicular to pedicelaxis, 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 stigma s.
  • 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 prostratestem, 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 prostratestem, 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, induratestamen 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.
Literature
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.

[FZ]

Podostemaceae, C. Cusset. Flora Zambesiaca 9:2. 1997

Morphology Stem
Stems simple or with abbreviated side shoots, leafless to ± densely leafy, and/or with reduced leaflets on flowering branches, or stems suppressed
Morphology Leaves
Leaves linear to filiform or reduced and scale-like (moss-like); linear leaves floating, entire or dichotomously, pinnately or laciniately divided, exstipulate or sometimes with 2 tooth-like stipules; scale-like leaves when present 3-ranked (tristichous) or 2-ranked (distichous), scattered or absent on the stems, and ± densely imbricate on branches and flowering shoots
Morphology Reproductive morphology Flowers
Flower hermaphrodite, small, actinomorphic or zygomorphic, without a spathella, or with a persistent membranous spathella (2 spathaceous bracts); spathella at first encloses the flower-bud and at anthesis tears irregularly at the apex allowing the pedicel to elongate bearing the flower erect beyond the spathella; flower-bud subtended by 2–3 free protecting bracts, or flower-bud at first inverted (reflexed) within a membranous spathella (also erect within the spathella outside the Flora Zambesiaca area)
Morphology Reproductive morphology Flowers Perianth
Perianth of 3 segments (tepals) connate in their lower part, or perianth reduced to 2 minute free filiform structures, lateral to, and shorter than, the androecium, or perianth absent
Morphology Reproductive morphology Flowers Androecium
Stamens hypogynous, 1 or 2 with filaments connate for at least one-third of their length; anthers 2-locular, dehiscing introrsely by a longitudinal slit
Morphology Reproductive morphology Flowers Gynoecium
Ovary sessile or on a gynophore, globose to ellipsoid, 1–2 or 3-locular with locules of equal or unequal size; locules ellipsoid to fusiform or subglobose, 2-lobed or not, placentation central or axile, bearing numerous anatropous ovules; styles 2 or 3, sessile or subsessile, usually free, variable in shape
Morphology Reproductive morphology Fruits
Capsule brown, spherical to ellipsoid or fusiform, smooth or adorned with ± wide longitudinal ribs, dehiscing in dry air into 2–3 equal and sometimes caducous valves, or 2 unequal valves of which only the smaller is caducous
Morphology Reproductive morphology Seeds
Seeds reddish-brown to blackish, minute, slightly flattened-ellipsoid to ovoid, exalbuminous; testa reticulate; embryo straight
Morphology General Habit
Plants of this family are moss-like freshwater herbs, almost always found in swift-flowing, permanent rivers, usually in turbulent waters of cataracts and waterfalls, or in continuous water-spray, often firmly fixed to rocks by a lichen-like thalloid basal part. Submerged and often annual the plants flower as they become exposed to air when water levels recede. Pollination is usually by insects, or by wind. Fruits develop rapidly after pollination. The seed coat is mucilaginous when wet and adheres to the substrate where it germinates Submerged freshwater herbs, firmly attached to rocks and stones in swift-flowing water or spray of waterfalls, often resembling mosses, liverworts or algae, habit also adapting to depth of water and receding water levels Plant base usually thalloid, variable in form and bearing endogenous buds on the margins and surface from which flowering shoots and stems arise

[FTEA]

Podostemaceae, H. J. Beentje, M.Sc., Ph.D., F.L.S.. Flora of Tropical East Africa. 2005

Morphology General Habit
Plant base usually thalloid, variable in form, without vessels, sometimes without xylem, bearing buds on the margins and surface from which shoots arise; thallus attached to the substrate by haptera, flattened disc-like organs excreting a cement-like substance, and sometimes with filiform rootlets; stem simple or with abbreviated side-shoots, sometimes suppressed Aquatic herbs, looking like mosses, lichens or algae and usually growing on rocks or stones submerged in fast-flowing water
Morphology Leaves
Leaves absent or, where present, alternate, entire to dissected, linear, filiform, or scale-like, 3-ranked or 2-ranked, sometimes densely imbricate on branches and flowering shoots; exstipulate or sometimes with 2 tooth-like stipules
Morphology Reproductive morphology Flowers
Flowers bisexual, regular or irregular, small, solitary or in cymes, sometimes cleistogamous; bracteoles 2, enclosing the flower (‘spathella’) and then tearing irregularly at anthesis allowing the pedicel to elongate beyond the spathella, or spathella absent and bracts subtending the flower; tepals absent or 2–3(–5), ± connate or free, or consisting of a small annular scale; stamens hypogynous, 1–2(–4), with the filaments usually at least basally connate, dehiscing introrsely with a longitudinal slit Flowers and fruits produced aerially at low water
Morphology Reproductive morphology Flowers Gynoecium
Ovary sessile or stalked, (1–)2(–3)-locular with as many ± basally connate (sub-)sessile stigmas; ovules many, anatropous, on thickened axile placentas
Morphology Reproductive morphology Fruits
Fruit a stalked capsule, smooth or ribbed, dehiscing into 2–3 valves in dry air; seeds usually many, very small, often with mucilaginous testa

Podostemaceae Rich. ex Kunth appears in other Kew resources:

First published in Nov. Gen. Sp. [H.B.K.] 1: ed. 4: 246. 1816 [4-11 May 1816] (1816)

Accepted by

  • APG IV (2016) http://dx.doi.org/10.1111/boj.12385

Flora Zambesiaca
Flora Zambesiaca
http://creativecommons.org/licenses/by-nc-sa/3.0

Flora of Tropical East Africa
Flora of Tropical East Africa
http://creativecommons.org/licenses/by-nc-sa/3.0

Flora of West Tropical Africa
Flora of West Tropical Africa
http://creativecommons.org/licenses/by-nc-sa/3.0

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2021. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Neotropikey
Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.
http://creativecommons.org/licenses/by/3.0