P. phegopteris (beechfern) is a graceful species with a black, slender root-stock, from which the pinnate fronds rise on long stalks, generally about 12 in.
There is evidence that the stem in some species was a climbing one; the pinnate leaves, arranged on the stem in a two-fifths spiral, were dimorphic, the sterile fronds resembling some forms of (From a drawing by Mrs D.
When the pinnate leaf of a Mimosa pudica, the so-called sensitive plant, is pinched or struck, the leaf droops rapidly and the leaflets become approximated together, so that their upper surfaces are in contact.
Elaboration in the form of the feelers, often a secondary sexual character in male insects, may result from a distal broadening of the segments, so that the appendage becomes serrate, or from the development of processes bearing sensory organs, so that the structure is pinnate or feather-like.
The date palm is a beautiful tree, growing to a height of from 60 to 80 ft., and its stem, which is strongly marked with old leaf-scars, terminates in a crown of graceful shining pinnate leaves.
They are all trees, usually of large size, with alternate stalked, unequally pinnate leaves, and abounding in an aromatic resinous juice.
In circumference, and bearing a crown of 6-9 very large spreading pinnate fronds.
Fraxinella is a very characteristic and attractive plant, 2 to 3 ft., with bold pinnate leaves, and tall racemes of irregular-shaped purple or white flowers.
High, with pinnate leaves, and masses of pinkish purple pea-like flowers.
P. coeruleum (Jacob's Ladder), 2 ft., has elegant pinnate leaves, and long panicles of blue rotate flowers.
A leaf with only a single midrib is said to be unicostate and the venation is described as pinnate or feather-veined.
19), the leaf is unequally pinnate (imparipinnate); when the leaflets or pinnae are placed alternately on either side of the midrib, and not directly opposite to each other, the leaf is alternately pinnate; and when the pinnae are of different sizes, the leaf is interruptedly pinnate.
In these plants the laminae or blades of the leaves are pinnate or bipinnate and are produced at the FIG.
- Imparipinnate (unequally pinnate) leaf of Robinia.
In Lathyrus Aphaca and some other plants the true pinnate leaves are abortive, the petiole forms a tendril, and the stipules alone are developed, perform ing the office of leaves.
In Cycas whorls of scales alternate with large pinnate leaves.
The Iceland poppy (P. undicaule), is one of the showiest species, having grey-green pinnate leaves and flowers varying in colour from pure white to deep orange-yellow, orange-scarlet, &c. Specially fine varieties with stalks 18-24 in.
- Stems tuberous or columnar, not infrequently branched, rarely epiphytic (Peruvian species of Zamia); fronds pinnate, bi-pinnate in the Australian genus Bowenia.
In a crown of long pinnate leaves.
- An expanded Alcyonarian zooid, showing the mouth surrounded by eight pinnate tentacles.
The latter are simple, or irregularly lobed in Ophioglossum, more or less compoundly pinnate in Botrychium and palmately pinnate in Helminthostachys.
The leaves, at the base of which are two large stipulelike outgrowths, have a thick leaf-stalk, and are simple or simply pinnate in Danaea, pinnate in Archangiopteris, bito tri-pinnate in Marattia and Angiopteris, and digitately lobed in Kaulfussia.
The leaves are large and pinnate; their lamina is usually thick, though filmy species of Todea occur.
- These forms have a horizontal rhizome, from which simply pinnate leaves arise in Platyzoma, while Gleichenia bears compound pinnate leaves with continued apical growth.
The leaves are simple and linear in Pilularia, but in Marsilia bear a pinnate four-lobed lamina.
P. Jaegeri), represented by large pinnate fronds not unlike those of existing species of Zamia, some Equisetaceous plants and numerous Ferns which may be referred to such families as Gleicheniaceae, Dipteridinae and Matonineae.
As examples of these doubtful forms may be mentioned Thinnfeldia, characteristic of Rhaetic and Lower Jurassic rocks; Dichopteris, represented by some exceptionally fine Jurassic specimens, described by Zigno, from Italy; and Ctenis, a genus chiefly from Jurassic beds, founded on pinnate fronds like those of Zamia and other Cycads, with linear pinnae characterized by anastomosing veins.
Sphenozamites, chiefly from French localities, which are referred to 1 fronds, which therg is good reason to refer to the Cycadales in the Cycads because of their similarity to the pinnate fronds of Upper Triassic, Rhaetic, Jurassic and Wealden rocks in India, modern Cycadaceae.
A number of hairy linear bracts enclose the whole; internal to these occur 12 to 20 crowded pinnate leaves (sporophylls), with their apical portions bent over towards the axis of the flower, the bases of the petioles being fused laterally into a disk surrounding the base of the conical receptacle.
Another well-known Cycadean genus is Williamsonia, so named by Mr Carruthers in 1870, and now applied to certain pinnate fronds - e.g.
Williamson was the first to express the opinion that the Bennettitean flowers known as Williamsonia were borne on the trunks which terminated in a crown of pinnate fronds of the type long known as Zamites gigas; this view was regarded by Saporta and others as incorrect, and the nature of the Bennettitean foliage was left an open question.
Its broad pinnate tropical leaf was pleasant though strange to look on.
Typically Marattiaceous sori, consisting of exannulate sporangia united to form synangia, are frequent, and are almost always found on fronds with the character of Pecopteris, large, repeatedly pinnate leaves, resembling those of Cyatheaceae or some species of Nephrodium.