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A new species of Brevianthus (Brevianthaceae, Marchantiophyta) from New Caledonia with unusual underleaf production.

Renner MA, Engel JJ, Patzak SD, Heinrichs J - PhytoKeys (2015)

Bottom Line: A second species, Brevianthushypocanthidium, is described as new and is the first record of the genus for New Caledonia.Among its distinguishing characters are its shallowly bilobed leaves, and triangular underleaves present on small to medium-sized shoot sectors, the lack of a hyaline leaf margin, and the crenulate leaf margin formed by heavily thickened external cell walls.To explain these features we propose a competitive model of shoot formation wherein the ventral merophyte progressively loses vigor as its relative stature decreases, and its derivative cells become discontinuous and isolated along the ventral stem surface, with intervening areas occupied by derivatives of the more vigorous lateral merophytes.

View Article: PubMed Central - PubMed

Affiliation: Royal Botanic Gardens & Domain Trust, Mrs Macquaries Road, Sydney, NSW 2000, Australia.

ABSTRACT
Brevianthus is a distinctive genus of leafy liverwort in its succubously inserted, entire leaves, lack of underleaves, restriction of sexual organs to lateral-intercalary branches, scattered rhizoids and dense leaf-surface ornamentation. The sole species, Brevianthusflavus, is divided into two subspecies, one in Tasmania the other in New Zealand. A second species, Brevianthushypocanthidium, is described as new and is the first record of the genus for New Caledonia. Among its distinguishing characters are its shallowly bilobed leaves, and triangular underleaves present on small to medium-sized shoot sectors, the lack of a hyaline leaf margin, and the crenulate leaf margin formed by heavily thickened external cell walls. The most unusual features of the new species are the presence of underleaves between lateral leaf insertion lines that reach the ventral stem mid-line, and the absence of underleaves from larger shoots. To explain these features we propose a competitive model of shoot formation wherein the ventral merophyte progressively loses vigor as its relative stature decreases, and its derivative cells become discontinuous and isolated along the ventral stem surface, with intervening areas occupied by derivatives of the more vigorous lateral merophytes.

No MeSH data available.


Related in: MedlinePlus

Ventral stem views. A, BBrevianthushypocanthidium (NSW791547) CBrevianthusflavussubsp.crenulatus (NSW745726) DBrevianthusflavussubsp.flavus (NSW892112).
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Figure 7: Ventral stem views. A, BBrevianthushypocanthidium (NSW791547) CBrevianthusflavussubsp.crenulatus (NSW745726) DBrevianthusflavussubsp.flavus (NSW892112).

Mentions: In small stature shoots of Brevianthushypocanthidium the leaf insertion lines do not reach the ventral stem mid-line, leaving a row or two of ventral cortical cell rows leaf-free, onto which the underleaves are inserted. In small stature shoots the merophyte rows appear both continuous and non-overlapping, and their growth is compatible with conventional liverwort development (Fig. 7).


A new species of Brevianthus (Brevianthaceae, Marchantiophyta) from New Caledonia with unusual underleaf production.

Renner MA, Engel JJ, Patzak SD, Heinrichs J - PhytoKeys (2015)

Ventral stem views. A, BBrevianthushypocanthidium (NSW791547) CBrevianthusflavussubsp.crenulatus (NSW745726) DBrevianthusflavussubsp.flavus (NSW892112).
© Copyright Policy - creative-commons-attribution
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4489084&req=5

Figure 7: Ventral stem views. A, BBrevianthushypocanthidium (NSW791547) CBrevianthusflavussubsp.crenulatus (NSW745726) DBrevianthusflavussubsp.flavus (NSW892112).
Mentions: In small stature shoots of Brevianthushypocanthidium the leaf insertion lines do not reach the ventral stem mid-line, leaving a row or two of ventral cortical cell rows leaf-free, onto which the underleaves are inserted. In small stature shoots the merophyte rows appear both continuous and non-overlapping, and their growth is compatible with conventional liverwort development (Fig. 7).

Bottom Line: A second species, Brevianthushypocanthidium, is described as new and is the first record of the genus for New Caledonia.Among its distinguishing characters are its shallowly bilobed leaves, and triangular underleaves present on small to medium-sized shoot sectors, the lack of a hyaline leaf margin, and the crenulate leaf margin formed by heavily thickened external cell walls.To explain these features we propose a competitive model of shoot formation wherein the ventral merophyte progressively loses vigor as its relative stature decreases, and its derivative cells become discontinuous and isolated along the ventral stem surface, with intervening areas occupied by derivatives of the more vigorous lateral merophytes.

View Article: PubMed Central - PubMed

Affiliation: Royal Botanic Gardens & Domain Trust, Mrs Macquaries Road, Sydney, NSW 2000, Australia.

ABSTRACT
Brevianthus is a distinctive genus of leafy liverwort in its succubously inserted, entire leaves, lack of underleaves, restriction of sexual organs to lateral-intercalary branches, scattered rhizoids and dense leaf-surface ornamentation. The sole species, Brevianthusflavus, is divided into two subspecies, one in Tasmania the other in New Zealand. A second species, Brevianthushypocanthidium, is described as new and is the first record of the genus for New Caledonia. Among its distinguishing characters are its shallowly bilobed leaves, and triangular underleaves present on small to medium-sized shoot sectors, the lack of a hyaline leaf margin, and the crenulate leaf margin formed by heavily thickened external cell walls. The most unusual features of the new species are the presence of underleaves between lateral leaf insertion lines that reach the ventral stem mid-line, and the absence of underleaves from larger shoots. To explain these features we propose a competitive model of shoot formation wherein the ventral merophyte progressively loses vigor as its relative stature decreases, and its derivative cells become discontinuous and isolated along the ventral stem surface, with intervening areas occupied by derivatives of the more vigorous lateral merophytes.

No MeSH data available.


Related in: MedlinePlus