Aridarum Ridl.
  • J. Bot. 51: 201 (1913) 


Notes: Distribution: NW. Borneo

General Description

Small to medium-sized, evergreen herbs. Stem decumbent, erect distal part sometimes rather long. Leaves several, spiral or rarely distichous (A. borneense); petiole sheathing only at base, with long, marcescent ligule; blade coriaceous, linear to elliptic, apex with tubular mucro; primary lateral veins pinnate, weakly or not differentiated, running into distinct marginal vein, higher order venation parallel-pinnate. Inflorescence solitary, sometimes more or less nodding; peduncle subequal to or longer than petiole, sometimes more or less deflexed at apex. Spathe stoutly ellipsoid, not constricted, convolute and gaping at apex only or broadly boat-shaped and widely gaping to base, lower part persistent, green, upper part caducous, white, cuspidate to acuminate at apex. Spadix sessile, cylindric, normally with a few sterile flowers at extreme base, female zone cylindric; pistil naked, shallow, laterally compressed, subhexagonal to subglobose; ovary 1-locular, ovules many, orthotropous to hemiorthotropous, funicle distinct, erect, placenta basal, stigma sessile, slightly concave centrally, as broad as ovary, usually more or less contiguous with neighbouring stigmas; sterile interstice short to absent, composed of sterile stamens; male zone subcylindric to ellipsoid; male flower 2-androus or not recognisable (unistaminate); filaments distinct to very short, free to connate, connective slightly to deeply excavated (rarely not excavated - A. incavatum), thecae either opposite or paired on one side of the anther and then situated inside or outside connective cavity, apically narrowed into long or short horn or needle, dehiscing by single apical pores; pollen inaperturate, ellipsoid-oblong, small (mean 23 mm, range 16-31 mm (Grayum, 1992: 21)), exine psilate. Infructescence a cluster of berries subtended by the obconic persistent lower spathe; berries globose or ellipsoid to cylindric, stigma remnant persistent; seeds ellipsoid, elongate, with long curved transparent interlinked micropylar appendages; testa longitudinally costate, embryo elongate, endosperm copious.

HABIT : small to medium-sized, evergreen herbs, stem decumbent, erect distal part sometimes rather long. LEAVES : several, spiral or rarely distichous (A. annae). PETIOLE : sheath with long, marcescent ligule. BLADE : coriaceous, linear to elliptic, apex with tubular mucro; primary lateral veins pinnate, weakly or not differentiated, running into distinct marginal vein, higher order venation parallel-pinnate. INFLORESCENCE : solitary, sometimes ± nodding. PEDUNCLE : subequal or longer than petiole, sometimes ± deflexed at apex. SPATHE : stoutly ellipsoid, not constricted, convolute and gaping at apex only or broadly boat-shaped and widely gaping to base, lower part persistent, green, upper part caducous, white, cuspidate to acuminate at apex. SPADIX : cylindric, normally with a few sterile flowers at extreme base, female zone cylindric, shorter than male and separated from it by equally thick zone of sterile male flowers, male zone equally thick, with shorter apical zone of sterile flowers, apex obtuse. FLOWERS : unisexual, perigone absent. MALE FLOWER : 1-2-androus, filaments distinct to very short, free to connate, connective slightly to deeply excavated, thecae either opposite or paired on one side and situated inside or outside connective cavity, apically narrowed into long or short horn, dehiscing by apical pore. POLLEN : inaperturate, ellipsoid-oblong, small (mean 23 µm., range 16-31 µm.), exine psilate. STERILE MALE FLOWERS : consisting of prismatic to obpyramidal, truncate staminodes with or without a small, central, apical cavity. FEMALE FLOWER : gynoecium shallow, laterally compressed, subhexagonal to subglobose, ovary 1-locular, ovules many, orthotropous to hemiorthotropous, funicle distinct, erect, placenta basal, stigma sessile, slightly concave centrally, as broad as ovary, contiguous with neighbouring stigmas. BERRY : globose or ellipsoid to cylindric, stigma remnant persistent, infructescence globular to slightly elongate. SEED : ellipsoid, elongate, testa longitudinally costate, embryo elongate, endosperm present.

Diagnostic Description

Rheophytes; petiole sheath with long marcescent ligule; blade apex with tubular mucro; spathe persistent in lower half, upper part caducous; thecae horned. Differs from Bucephalandra and Phymatarum in spathe stout, not constricted, spadix with short apical zone of sterile flowers but lacking a conspicuous appendix, stigma as broad as ovary.

Habitat

All species are rheophytic, sometimes facultatively lithophytic or terrestrial in forest, usually in deep shade, from the lowlands to lower montane forests.

Tropical humid forest; rheophytes.

Distribution

Nine species, all endemic to Borneo.

NW. Borneo.

Distribution Map

 
  • Native distribution
Specimens
Found in
  • Asia-Tropical Malesia Borneo

  Bibliography

  • 1 Govaerts, R. & Frodin, D.G. (2002). World Checklist and Bibliography of Araceae (and Acoraceae): 1-560. The Board of Trustees of the Royal Botanic Gardens, Kew.
  • 2 Govaerts, R. (1995). World Checklist of Seed Plants 1(1, 2): 1-483, 1-529. MIM, Deurne.
  • 3 Bogner, J. & Hay, A. Schismatoglottideae (Araceae) in Malesia 2: Aridarum, Bucephalandra, Phymatarum and Piptospatha Telopea. Telopea; Contributions from the National Herbarium of New South Wales 9, 222 (2000).
  • 4 Gardens, K.""Royal Bot World Checklist of Selected Plant Families. (2008).
  • 5 Mayo, S.J., Bogner, J. & Boyce, P.C. The Genera of Araceae. (Royal Botanic Gardens Kew: 1997).

 Information From

CATE Araceae
http://araceae.e-monocot.org
Haigh, A., Clark, B., Reynolds, L., Mayo, S.J., Croat, T.B., Lay, L., Boyce, P.C., Mora, M., Bogner, J., Sellaro, M., Wong, S.Y., Kostelac, C., Grayum, M.H., Keating, R.C., Ruckert, G., Naylor, M.F. and Hay, A., CATE Araceae, 14 Dec 2011 . 17 Dec 2011.
  • A All Rights Reserved
Global Biodiversity Information Facility
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eMonocot
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eMonocot. (2010, 1st November). Retrieved Wednesday, 8th February, 2012, from http://e-monocot.org.
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World Checklist of Selected Plant Families
http://apps.kew.org/wcsp/
WCSP 2014. 'World Checklist of Selected Plant Families. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://apps.kew.org/wcsp/ Retrieved 2011 onwards
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