Vernation

Vernation

Vernation (from vernal meaning spring, since that is when leaves spring forth in temperate regions) is the formation of new leaves or fronds. In plant anatomy, it is the arrangement of leaves in a bud.

In pine trees new leaves are short and encased in sheaths. Each leaf bundle consists of 2 to 5 needles. All the leaves on one section of branch grow in length together. In the cabbage, new leaves are folded over, each covered by the previous leaf.

Contents

Circinate vernation

This fern is producing a new frond by the process of circinate vernation.

Circinate vernation is the manner in which a fern frond emerges. As the fern frond is formed, it is tightly curled so that the tender growing tip of the frond (and each subdivision of the frond) is protected within a coil. At this stage it is called a crozier (after the shepherd's crook) or fiddlehead (after the scrollwork at the top of a violin). As the lower parts of the frond expand and toughen up, they begin to photosynthesize, supporting the further growth and expansion of the frond. In the case of many fronds long hairs or scales provide additional protection to the growing tips before they are fully uncoiled. Circinate vernation may also be observed in the extension of leaflets, in the compound leaves of Cycads.[1] Circinate vernation is also typical of the carnivorous plant family Droseraceae,[2] for example see this photo of Drosera filiformis.

Convolute vernation

This hosta leaf is produced by convolute vernation.

The process of convolute vernation involves the wrapping of one margin of the leaf's blade over the other. This folding mechanism makes the emerging leaf look like a tube.

Involute vernation

These cycad leaves are produced by involute vernation.

In involute vernation both margins on opposing sides of the leaf are rolled up forming two tubes that meet at the midrib of the leaf.

See also

  • Aestivation — the way in which the petals and sepals of a flower are arranged in a bud.
  • Ptyxis — the way an individual leaf is folded within a bud.

References

  1. ^ [1]
  2. ^ Cameron, K. M.; Wurdack, K. J.; Jobson, R. W. (2002), "Molecular evidence for the common origin of snap-traps among carnivorous plants", American Journal of Botany 89 (9): 1503, doi:10.3732/ajb.89.9.1503 

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  • vernation — [ vɛrnasjɔ̃ ] n. f. • 1826; lat. vernatio ♦ Bot. Disposition des feuilles ou des pièces florales dans le bourgeon, qui indique la préfoliation ou la préfloraison. ● vernation nom féminin Préfoliation. Préfloraison. ⇒VERNATION, subst. fém. BOT.,… …   Encyclopédie Universelle

  • Vernation — Ver*na tion, n. [F. vernation: cf. L. vernatio the sloughing of the skin of snakes.] (Bot.) The arrangement of the leaves within the leaf bud, as regards their folding, coiling, rolling, etc.; prefoliation. [1913 Webster] …   The Collaborative International Dictionary of English

  • Vernation — (v. lat.), 1) das Ausschlagen der Gewächse im Frühling; 2) das Häuten gewisser Thiere …   Pierer's Universal-Lexikon

  • vernation — [vər nā′shən] n. [ModL vernatio < pp. of L vernare, to be verdant < ver, spring: see VERNAL] Bot. the arrangement of leaves in a leaf bud …   English World dictionary

  • Vernation — Ver|na|ti|on 〈[vɛr ] f. 20〉 Lage der einzelnen Knospenblätter [<lat. vernare „sich verjüngen“] * * * Vernation   [lateinisch, eigentlich »das Sichhäuten der Schlange im Frühling«] die, / en, Knospenlage, Botanik: Bezeichnung für die Lage der… …   Universal-Lexikon

  • vernation — noun Etymology: New Latin vernation , vernatio, from Latin vernare to behave as in spring, from vernus vernal Date: 1793 the arrangement of foliage leaves within the bud …   New Collegiate Dictionary

  • Vernation — Als Knospenlage oder Vernation wird in der Botanik die Lage der Blätter in der Knospe bezeichnet. Die Knospenlage ist häufig spezifisch für bestimmte Verwandtschaftsgruppen. Es werden folgende Typen der Knospenlage unterschieden: circinat oder… …   Deutsch Wikipedia

  • vernation — /veuhr nay sheuhn/, n. Bot. the arrangement of the foliage leaves within the bud. [1785 95; < NL vernation (s. of vernatio), equiv. to L vernat(us) (ptp. of vernare to be verdant; see VERNAL, ATE1) + ion ION] * * * …   Universalium

  • vernation — (vèr na sion) s. f. Terme de botanique. Arrangement des feuilles dans le bourgeon, dit aussi préfoliation. •   M. le Dr Clos.... s attache à faire ressortir l importance des caractères tirés de la vernation ou préfoliation pour les… …   Dictionnaire de la Langue Française d'Émile Littré

  • vernation — noun a) The appearance of new leaves. b) The arrangement of multiple organs (such as leaves and flower parts) within a bud. See Also: prefloration, prefoliation, ptyxis …   Wiktionary

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