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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 ?
A 3 mm X 5 mm square leaf sample was sectioned from the centre of a pinnule (leaflet) (between the midrib and the pinnule margin) collected from a central pinna.
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.
1) on the basis of the overall morphology, size and pinnule shape and despite the indistinct venation.
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.
2004), though this striping may in fact be homologous, and only the pinnule arrangement differs between the two species.
In a quantitative analysis of pinnule formation in Adiantum and Cheilanthes, mitotic rates were compared for different developing leaf sectors (Zurakowski & Gifford, 1988).
Caulerpa cupressoides (Figure 1A) is characterized by a creeping axis fixed to the substrate by rhizoids pinnules arranged in the opposite direction, endowed with erect shoots (assimilative) pine tree-shaped distributed around the main axis (TRI, 2009).