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Record: oai:ARNO:535029

AuthorJohanna H.A. van Cittert
TitlePalaeobotany of the Mesophytic II. New and noteworthy jurassic ferns from Yorkshire
JournalMededelingen van het Botanisch Museum en Herbarium van de Rijksuniversiteit te Utrecht
AbstractDiagnosis: Frond at least bipinnate. Rachis up to 2 mm broad, longitudinally grooved. Pinnae alternate or subopposite, up to 1,5 cm broad (normally 1 cm), longest one 5 cm long but without apex. Pinnae arising at intervals of 1-2,5 cm, and at an angle of 30-60°. Pinna-rachis thin. Pinnules arising at an angle of 45° at intervals of 1-6 mm, alternate, katadromic. Pinnules always united basally. Pinnules in the lower (or middle) part of the leaf linear, up to 1,5 cm long (normally 1 cm) and up to 4 mm broad (normally 2 mm). Apex obtuse, margin entire, slightly narrowed near the base, basal margin decurrent as a narrow wing along the pinna-rachis. In the upper part of the leaf pinnules smaller, 4 mm broad, 6 mm long, deltoid and slightly falcate. Proximally the pinnae are pinnulate, the pinnules becoming first laterally fused and then forming an entire pinna.
Venation: Midrib arising at a small angle near the basal edge of the pinnule and bending outwards or, sometimes, straight to the apex. Lateral veins arising in katadromic order or nearly opposite, at intervals of 1-2 mm and at an angle of 40°, simple or once forked half-way towards the margin; branches diverging.
Document typearticle
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