| 释义 |
pinnate, a.|ˈpɪnət|
[ad. L. pinnāt-us feathered, winged, f. pinna feather, wing: see pinna2 and -ate2.]
1. Nat. Hist. Resembling a feather; having lateral parts or branches on each side of a common axis, like the vanes of a feather.
a. Bot. Applied to a compound leaf having a series of (sessile or stalked) leaflets arranged on each side of a common petiole, the leaflets being usually opposite, sometimes alternate (alterni-pinnate); also to more complex leaves of the same kind, in which the leaflets, thus arranged, are borne on secondary, tertiary, etc. petioles which are themselves similarly arranged (bipinnate, tripinnate, etc.).
interruptedly pinnate: see quot. 1861.
[1704J. Harris Lex. Techn. I, Pinnata Folia, in Botany.] 1727Bailey vol. II, Pinnate, deeply jagged or indented (spoken of the Leaves of Plants) resembling Feathers. 1760J. Lee Introd. Bot. ii. xxxi. (1765) 152 Asplenium, with pinnate Leaves. 1861Bentley Man. Bot. 169 It is interruptedly pinnate..when the leaflets are of different sizes, so that small pinnæ are..intermixed with larger ones, as in the Potato and Silver Weed. 1872Oliver Elem. Bot. i. vii. 77 Compound leaves are either of the pinnate type, as Rose, or of the digitate type, as Horse Chestnut.
b. Zool. Having branches, tentacles, or other lateral parts arranged on each side of an axis; in Entom. applied to a surface (as in the legs of grasshoppers) marked with minute parallel lines on each side of a central ridge.
1846Dana Zooph. iv. (1848) 73 The budding polyps are sometimes confined to two opposite sides of a branch, and pinnate forms result. 1854Woodward Mollusca ii. 191 Gills pinnate, placed round the dorsal vent. 1858Lewes Sea-side Stud. 87 The tentacular filaments..are numerous, each forming a little tree with pinnate branches. 1875C. C. Blake Zool. 200 The tail is pinnate at the point.
c. Physical Geogr. Of a drainage pattern: resembling a feather in plan.
1932E. R. Zernitz in Jrnl. Geol. XL. 512 These acute-angled joinings with the rather evenly spaced and parallel tributaries form a pattern so much like that of a feather that it might appropriately be called ‘pinnate’... Figure 8 is an example of pinnate drainage. 1942O. D. von Engeln Geomorphol. xi. 215 All the other recognized types of drainage pattern: rectangular, trellis, annular, pinnate, contorted, are responses to structure. 1968R. W. Fairbridge Encycl. Geomorphol. 287/2 Modified dendritic drainage may be described as pinnate, sub-parallel or anastomatic.
2. Zool. Having feathers, wings, fins, or similar parts. rare—0. (Cf. next, 2.)
1890in Cent. Dict. |