Epidendrum rigidum

Epidendrum rigidum is an epiphytic reed-stemmed Epidendrum orchid common throughout the Neotroical lowlands, below 600 m. (The Fora of North America[1] recognizes a distinct species, E. cardiophorum Schltr., which replaces E. rigidum in Mexico and Central America; Kew lists E. cardiophorum Schltr. as a synonym for E. rigidum.[2])

Epidendrum rigidum
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Epidendroideae
Genus: Epidendrum
Subgenus: Epidendrum subg. Epidendrum
Section: Epidendrum sect. Planifolia
Subsection: Epidendrum subsect. Spathacea
Species:
E. rigidum
Binomial name
Epidendrum rigidum
Synonyms

Epidendrum pium Rchb.f. & Warm.
Epidendrum cardiophorum Schltr.
Spathiger rigidus (Jacq.) Small

Description

E. rigidum has been placed in the subgenus E. subg Epidendrum Lindl. (1841)[3] because its sympodial stems do not thicken to form pseudobulbs, its stems are covered by the basal sheaths of its distichous leaves, and its peduncle emerges from the apical leaf without being covered by any bract or sheath. The basal parts of the stems unite to form a creeping rhizome; the upper parts grow to 20 cm long and can assume erect, horizontal, or hanging postures.[4] The lathery ovate-oblong obtuse leaves are 3–8 cm long and apically bilobed. As with other members of E. subsect. Spathacea Rchb.f. 1861, the racemose inflorescence bears enlarged spathaceous floral bracts. The green, non-resupinate, fleshy flowers are partially covered by the large, dolabriform bracts. The ovate obtuse sepals are 5 mm long, with the lateral sepals larger than the dorsal sepal. The linear petals are also 5 mm long. As with other members of the genus Epidendrum, the lip is adnate to the column to its apex. The lip is heart-shaped where it diverges from the column, ovate, and obtuse at the apex.

The diploid chromosome number of E. rigidum has been determined as 2n = 40.[5]

Homonymy

References

  1. Flora of North America 26(609)downloaded in October, 2009 from http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242101582
  2. http://apps.kew.org/wcsp/
  3. H. G. Reichenbach item 307 of "ORCHIDES" in C. Müller: Walpers. Annales Botanices Systematicae VI(1861) p. 400
  4. C. Dodson & R. Vásquez "EPIDENDRUM RIGIDUM Jacq.", Plate 0334 in C. Dodson, Ed. Icones Plantarum Tropicarum, Series II Orchids of Bolivia Missouri Botanical Garden, St. Louis. 1989.
  5. page 252. Leonardo P. Felix and Marcelo Guerra: "Variation in chromosome number and the basic number of subfamily Epidendroideae (Orchidaceae)" Botanical Journal of the Linnean Society 163(2010)234-278, The Linnean Society of London
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