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Titolo:
BIOMECHANICS AND FUNCTIONAL-ANATOMY OF HOLLOW STEMMED SPHENOPSIDS - III - EQUISETUM HYEMALE
Autore:
SPECK T; SPECK O; EMANNS A; SPATZ HC;
Indirizzi:
UNIV FREIBURG,BOT GARTEN,PLANT BIOMECH GRP,SCHANZLESTR 1 D-79104 FREIBURG GERMANY INST BIOL 3 D-79104 FREIBURG GERMANY
Titolo Testata:
Botanica acta
fascicolo: 5, volume: 111, anno: 1998,
pagine: 366 - 376
SICI:
0932-8629(1998)111:5<366:BAFOHS>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
PLANTS;
Keywords:
BIOMECHANICS; VISCOELASTICITY; FUNCTIONAL ANATOMY; PLANTS; EQUISETUM HYEMALE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
37
Recensione:
Indirizzi per estratti:
Citazione:
T. Speck et al., "BIOMECHANICS AND FUNCTIONAL-ANATOMY OF HOLLOW STEMMED SPHENOPSIDS - III - EQUISETUM HYEMALE", Botanica acta, 111(5), 1998, pp. 366-376

Abstract

As in Equisetum giganteum, the hollow stem of Equisetum hyemole owes the mechanical stability of the internodes to an outer ring of strengthening tissue (hypodermal sterome) which provides stiffness and strength in the longitudinal direction. In contrast to hollow-stemmed grasses, the hypodermal sterome consists of living cells. The compound innertissue of the overwintering aerial stem of Equisetum hyemale includesa continuous inner and outer endodermis layer of vital thick-walled cells that have slightly lignified Casparian thickenings. The two endodermis layers provide an inner tension and compression bracing which lend resistance to local buckling. The stress-strain relation in longitudinal tension is biphasic with remarkably high critical strains especially in the upper parts of the stem. Scraping off part of the epidermis with the built-in silicate does not change this behaviour, except inthe initial steep part of the curve where the Young's modulus is reduced by 20%. No contribution of the endodermis and the parenchyma couldbe detected in tension tests of longitudinally-oriented strips. Relaxation experiments reveal viscoelastic behaviour. As with the biphasic stress-strain relation and the critical strains, the viscoelastic properties have largely to be ascribed to the hypodermal sterome.

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Documento generato il 05/12/20 alle ore 10:29:30