Steereochila ecuadorica Inoue
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Authority
Buck, William R. 1987. Bryostephane Steereana: A Collection of Bryological Papers Presented to William Campbell Steere On The Occasion of His 80th Birthday. Mem. New York Bot. Gard. 45: 1-749.
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Family
Plagiochilaceae
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Scientific Name
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Description
Latin Diagnosis - Planta mediocris vel major, 4-7 cm longa et 4-5 mm lata, luteo-brunneola; caulis 450 µm usque crassus, validus brunneus, supeme moderate ramosus, typo ventrali-terminali; apices ramorum ramosissimorum, proliferentes; folia caulina approximata, oblique patula, 2-2.6 mm longa et 1.8-2.5 mm lata, plano-disticha, late ovata vel ovato-trigona, margine antico stricta, nuda, longe decurrentia, apice anguste rotundata, integra vel 1-5-dentata, postice arcuata, integra vel 1-3-dentata, basi ampliata, baud decurrentia; foliorum cellulae medianae 35-45 x 35-48 µm, basales 35-43 x 40-60(-70) µm, parietibus tenuibus, trigonis acutis vel subnodulosis, cuticula laevi.
Species Description - Plants medium- or large-sized, more or less robust, 4-7 cm long and 4-5 mm wide, pale yellowish brown, erectly or obliquely ascending, without differentiated creeping stem. Stem about 450 µm thick, dorsal surface moderately or broadly exposed, in cross section about 22 cells across, the cortical cells in (3-)4 layers, very thick-walled (walls as thick as 6-10 µm), bright to deep brown, cell cavities 10-15 x 13-25 µm, the interior cells thin-walled, 18-25 x 25-40 µm, trigones absent; branches moderate in number, usually developed on distal half of shoot, always of the terminal type, developed from ventral merophyte, apices of branches usually gemmiferous, forming clusters. Leaves approximate, obliquely spreading, dorsal margin weakly revolute, long-decurrent along dorsal stem-midline, ventral leaf-bases not decurrent, extending to the ventral midline of stem and sometimes virtually united with the base of opposite leaf, ventral merophyte 0-1 at middle to lower portion of shoot, 5-6 cells wide at distal portion of shoot where the ventral, terminal-branches developed; flat leaves broadly ovate or ovate-triangular, on distal part of shoot ovate-oblong, 1.8-2.5 mm wide and 2-2.6 mm long and 1-1.2 times as long as wide on middle portion of shoot, dorsal margin straight (or nearly so), entire, apex narrowly rounded, entire or with 1-5 teeth, ventral margin nearly straight from dilated basal margin, entire or sometimes with 1-3 teeth on distal half, leaves on distal portion of shoot nearly always bilobed to 35-43 the length, otherwise entire; ceUs 35- 45 X 35-48 µm at leaf-middle, 35-43 x 40-60(-70) µm at leaf base, walls thin, trigones medium- or large-sized, acute or subnodulose, cuticle smooth. Underleaves absent. Asexual reproduction frequent, by means of propagula gregariously developed at apices of terminal branches, propagula thread-like, one-layered and 1-4 cell-rowed formed from deformed leaves or 3-4-layered with 1-2-celled protuberances formed from deformed branches.
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Discussion
Figs. 1,2.
Type: ECUADOR. Carchi: Cordillera Occidental, west slope, Tulcan-Maldonado road, on moist roadside bank, alt. 9500 ft., W. C. Steere 26580 (holotype ny, isotype TNS).
This monotypic genus appears to be closely related to Plagiochila, and the diagnostic characteristics for the separation of it from that genus are: 1) the moderate number of ventral, terminaltype branches on distal portions of shoots (especially near shoot apex), and 2) the frequent propagula derived from the repeated ramifications of apical portions of branches, thus forming clusters of thread-like propagula on the apices of branches ofthe terminal-type. The gemmiferous branches forming clusters are easily caducous and the small, bifid leaves around the branches are also very caducous, dropping off from the base.
In the Plagiochilaceae, the branches of terminal- type are reportedly always of the Frullania- type, developing from the lateral merophyte, as is commonly observed in the genus Plagiochila. Other genera of this family possess the branches of lateral-intercalary type (of the Plagiochila- type) or ventral-intercalary type. In Steereochila, the ventral merophyte is extremely narrow in the basal to middle portion ofthe stem (being 0-1 cell broad), but it is rather suddenly broadened to 5-6 cells in width (or rarely to 10 ceUs) in the distal portion ofthe stem where the terminal-type branch may develop. Although there was observed no underleaf developed on the shoot, at the base of the terminal branch nearly always one small, lanceolate underleaflike appendage develops but this condition seems not to be constant; I have observed such underleaf- like appendages in the first to fourth branch on a shoot but other branches (near branch-apex) do not have them. This branch-type seems to be ofthe Acromastigum-type ofthe terminal branch which has been known only in some genera of the Lepidoziaceae.
In the basal to middle portion of stem, the ventral bases of leaves extend to the ventral stemmidline and superficially they look "united," thus seemingly similar to the case of Plagiochilion. However, in Steereochila no ventral-intercalary branches develop as in Plagiochilion.
The propagula seen in the Plagiochilaceae are developed on the ventral surface of leaves. Sometimes young shoots developed from propagula form clusters on leaves, as frequently seen in Plagiochila excisa Steph. and others. A peculiar type of propagula is observed in Xenochila, in which the propagula are multicellar, globose to oblong in shape, deeply green and developed on the margin of scale-like leaves. The propagula of Steereochila are formed from repeatedly divided branch-apices and deformed leaves on these branches, thus correctly they are not true propagula but caducous branches or "cladia" and caducous, deformed "leaves." However, these "cladia" and "leaves" are morphologicaUy very similar to propagula developed on normal leaves.