Ontogeny of the Open Dichotomous Venation in the Pinna of the Fern Nephrolepis

Abstract

Pray, Thomas r. (U. South. California, Los Angeles.) Ontogeny of the open dichotomous venation in the pinna of the fern Nephrolepis. Amer. Jour. Bot. 47(5) : 319—328. Illus. 1960.–The venation of the pinna of Nephrolepis consists of a midvein and 2 lateral series of dichotomizing veins all of which terminate freely near the margins. The development of the pinna is analyzed with particular attention to the nature of the marginal meristem and the organization of the embryonic pinna as it appears in paradermal section. The arrangement of cells in pinna wings during the period of marginal growth displays a pattern which foreshadows the pattern of the mature venation. In contrast with the development of the leaves of angiosperms, marginal growth continues into a relatively late phase of pinna ontogeny and apparently is active throughout the phases of ontogeny concerned with blocking‐out the pathways of procambial differentiation. Thus the pattern of venation appears to be correlated with the manner of activity of the marginal meristem and subsequent orientation of its derivatives. The theoretical aspects of the result of this investigation are discussed in relation to other studies of foliar venation ontogeny.

Ecology And Growth Habit Of Laveineopteris: A Gymnosperm from the Late Carboniferous Tropical Rain Forests

“…guttates for fertilization purposes (Roshchina and Roshchina 1993). Ferns can also guttate (Pray 1960;Hovenkamp 1996), as can horsetails. The hydathodes of Equisetum have a poorly developed epithem, but are not associated with the free tips of vascular elements (Johnson 1937).…”

Patterns of segregation and convergence in the evolution of fern and seed plant leaf morphologies

“…Living plants provide a developmental con text for this evolutionary history. Marginal growth is found in fern laminae (Pray 1960(Pray , 1962; Zurakowski and Gifford 1988) that have one or two orders of veins with strictly mar ginal vein endings. A causal link between these morphological and developmental traits is consistent with current understanding of vascular differentiation along gradients of the hormone auxin produced in growing areas (e.g., Sachs 1991;Berleth et al 2000).…”

Cuticles of Lescuropteris genuina from the Stephanian (Upper Carboniferous) of Central France: evidence for a climbing growth habit

“…The pinnules of L. genuina show a number of features which enable an ecological interpretation of this taxon. Thickenings at the endings of the veins of L. genuina seem very similar to the hydathodic masses consisting of short broad tracheary elements, occurring in recent ferns with an open dichotomous venation (Potonit, 1892;Haberlandt, 1894;Pray, 1960). In these ferns such structures end below the upper leaf epidermis and normally terminate in a distinct water pit (Potonit, 1892).…”