scalariform


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scalariform

[skə′lar·ə‚fȯrm]
(biology)
Resembling a ladder; having transverse markings or bars.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Axial parenchyma and (indirectly) rays, vessel grouping, narrowing of vessels, and presence of tracheids and other mechanisms provide conductive safety in angiosperms and supersede scalariform perforation plates.
Vessel-ray pits with much reduced borders to apparently simple, with pits rounded or angular and horizontal (scalariform, gashlike) to vertical (palisade) were found in A.
Finding scalariform tracheids attached to Artisia (his Sternbergia) pith casts, Dawson assumed that at least some of these fossils must have belonged to Sigillaria, based on the common occurrence of scalariform tissue in that plant (Dawson 1859).
integra have nine layers of scalariform thickenings in the radial walls as compared to three in C.
Remarks: The deeply impressed suture, the scalariform whorls, and the slight terminally twisted columella immediately distinguish Rectaxis pagodus from R.
Protoxylem tracheids, 6-12 [micro]m in diameter, are characterised by annular and spiral thickening with scalariform and transitional pitting seen on the 9-15 [micro]m diameter metaxylem tracheids (Fig.
Perforation plates predominantly simple; variously scalariform plates occasional (Fig.
Sieve plates are scalariform and show low lignification of cell walls.
Bailey & Tupper (1918) offered a muchreproduced drawing schematizing the tracheid as a primitive type of tracheary element in angiosperms; from this, vessels (first with scalariform, ultimately simple perforation plates) were progressively derived on the one hand, whereas on the other hand, imperforate tracheary elements progressively lost pit borders and changed (by implication, gradually) from conductive to mechanical cells.
Cheadle (1942) also offers some gradate phylogenetic progressions, based mostly on the end walls of vessel elements: long scalariform perforation plates are considered indicative of "primitive" conditions, simple perforation plates are considered at the opposite extreme, indicators of specialization.
The polarity of the tracheid-vessel transition and that from tracheid-like vessel elements that were long and narrow with scalariform pitting and perforation plates to short, wide elements with alternate pitting and simple perforation plates was then used to anchor inferences regarding a suite of other characters in the wood given their association with vessels of a given "level of specialization" (Table 1).