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Related to pinnule: pinnation


 (pĭn′yo͞ol) also pin·nu·la (pĭn′yə-lə)
n. pl. pin·nules also pin·nu·lae (pĭn′yə-lē′)
1. Botany One of the secondary divisions of a binnately compound leaf.
2. Zoology A small featherlike part or subdivision of an appendage, especially one of the small branches on the arm of a crinoid.

[Latin pinnula, diminutive of pinna, feather; see pet- in Indo-European roots.]

pin′nu·lar adj.


(ˈpɪnjuːl) or


n, pl pinnules or pinnulae (ˈpɪnjʊˌliː)
1. (Botany) any of the lobes of a leaflet of a pinnate compound leaf, which is itself pinnately divided
2. (Zoology) zoology any feather-like part, such as any of the arms of a sea lily
[C16: from Latin pinnula, diminutive of pinna feather]
ˈpinnular adj


(ˈpɪn yul)

1. a part or organ resembling a barb of a feather, a fin, or the like.
2. a secondary pinna, one of the pinnately disposed divisions of a bipinnate leaf.
[1585–95; < Latin pinnula, diminutive of pinna feather; see -ule]
pin′nu•lar (-yə lər) adj.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.pinnule - division of a usually pinnately divided leafpinnule - division of a usually pinnately divided leaf
leaflet - part of a compound leaf
References in periodicals archive ?
We confirm the usefulness and constancy of these characters except for pinnule arrangement, which we find variable in all four species.
At the end of each of the small divisions of the compound leaflet there is, when the leaf first unfolds, a little yellow fruit-like body united by a point at its base to the end of the pinnule.
Of these, most are attached to fragmentary, ultimate pinnae (Halle 1927, 1933; Arnold 1937; Zodrow and McCandlish 1980b) without pinnule replacement, or to fragmentary axes (Drinnan et al.
Within Eupolypods I, the genus can almost always be distinguished by a character of its venation: in the proximal portions of the pinna, the veinlet that supplies the basal basiscopic lobe or segment of a pinnule springs from the costule; however, distally along the pinna rachis, the segments or lobes become successively more adnate and decurrent on the pinna rachis, and the veinlet supplying the lobe or segment springs from the pinna rachis, not the costule (Christensen 1920, Holttum 1986, Smith and Moran 1987).
Adaxial and abaxial midveins of one pinnule also show different widths, epidermal morphologies, and differing degrees of cutinization.
Venation of pinnule or ultimate axis: 0 = not anastomosing; 1 = anastomosing.
0 cm long, equilateral, the segments adnate, often with the basal basiscopic pinnule enlarged and slightly more lobed on the basiscopic side; pinna rachises abaxially eglandular, sparsely pubescent (sometimes apparently without hairs], scaly, the hairs 0.
Blades 3-pinnate to 3-pinnatifid or 4-pinnate; ultimate pinnule segments narrow, linear or linear-lanceolate, 0.