Circinate vernation is also typical of the carnivorous plant family Droseraceae, for example see this photo of Drosera filiformis. It is also seen in the closely related genera Drosophyllum and Triphyophyllum, and in the much more distantly related Byblis; however in these three genera, the leaves are coiled outwards towards the abaxial surface of the leaf (reverse circinate vernation): this appears to be unique to these three plants among the angiosperms .
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This fern is producing a new frond by the process of circinate vernation. Circinate vernation is the manner in which a fern frond emerges. As the fern frond is formed, it is tightly curled so that the tender growing tip of the frond (and each subdivision of the frond) is protected within a coil. At this stage it is called a crozier (after the shepherd's crook) or fiddlehead (after the scrollwork at the top of a violin).
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Hao and Xue in 2013 used the absence of terminal sporangia to place the genus in the paraphyletic order Gosslingiales, a group considered to have indeterminate growth, with fertile branches generally showing circinate vernation (initially curled up).
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Like other zosterophylls, members of the Sawdoniales bore lateral, reniform sporangia. They branched dichotomously, and grew at the ends by unrolling (circinate vernation). Some had smooth stems, others were covered in small spines; fungal bodies have been reported in some spines.
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Presence or absence of spines has been used as a diagnostic factor to distinguish between species. Young fronds are frequently covered with scales or spines. They uncurl by circinate vernation. The sori are circular and present on the underside of the pinnules away from the margins (edges).
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Drosera filiformis, commonly known as the thread-leaved sundew, is a small, insectivorous, rosette-forming species of perennial herb. A species of sundew, it is unusual within its genus in that the long, erect, filiform (thread-like) leaves of this plant unroll in spirals – an arrangement similar to the circinate vernation seen in ferns.
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Hao and Xue in 2013 used the absence of terminal sporangia to place the genus in the family Gosslingiaceae in the paraphyletic order Gosslingiales, a group considered to have indeterminate growth, with fertile branches generally showing circinate vernation (initially curled up). Kenrick and Crane in 1997 also placed the genus in the family Gosslingiaceae, but they place this family in the order Sawdoniales.
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Hao and Xue in 2013 used the absence of terminal sporangia to place the genus in the paraphyletic order Gosslingiales, a group of zosterophylls considered to have indeterminate growth, with fertile branches generally showing circinate vernation (initially curled up). Kenrick and Crane in 1997 also placed the genus in the family Gosslingiaceae, but they place this family in the order Sawdoniales.
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Asplenium nidus forms large simple fronds visually similar to banana leaves, with the fronds growing to long and broad. They are light green, often crinkled, with a black midrib, and exhibit circinate vernation. Spores develop in sori on the underside of the fronds. These sori form long rows extending out from the midrib on the back of the outer part of the lamina (frond).
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Left on the plant, each fiddlehead would unroll into a new frond (circinate vernation). As fiddleheads are harvested early in the season before the frond has opened and reached its full height, they are cut fairly close to the ground. Fiddleheads have antioxidant activity, are a source of omega-3 and omega-6 fatty acids, and are high in iron and fibre. Certain varieties of fiddleheads have been shown to be carcinogenic.
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Fern fronds, as with all leaves, arise from the stem, either directly, or on an outgrowth from the stem termed a phyllopodium. The stem of a typical (leptosporangiate) fern is subterranean or horizontal on the surface of the ground. These stems are called rhizomes. Many fern fronds are initially coiled into a fiddle-head or crozier (see circinate vernation), although cycad and palm fronds do not have this pattern of new leaf growth.
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491 A cladogram published in 2004 by Crane et al. places Discalis in a paraphyletic stem group of broadly defined "zosterophylls", basal to the lycopsids (living and extinct clubmosses and relatives). Hao and Xue in 2013 used the absence of terminal sporangia to place the genus in the paraphyletic order Gosslingiales, in the family Discaliaceae. The Gosslingiales are considered to be zosterophylls with indeterminate growth and fertile branches generally showing circinate vernation (initially curled up).
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The scapes emerge vertically, lacking the circinate vernation of its leaves and all other scapes of the genus Drosera, with the exception of D. arcturi. The scapes consist of two primary branches and bear 5 to 20 (sometimes 30) unscented pink flowers with long petals. Bracts are small, bearing some reduced tentacles. Each flower has three unbranched, spreading styles emerging from the top of the ovary and extending beyond the five erect stamens (15 mm long), which surround the ovary.
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The pillwort, along with all other aquatic ferns in the order Salviniales, exhibits heterospory and forms hard, seed-like sporocarps, as do the other members of the order. The sporocarps are distinctly different from the closely related genus Marsilea because they are globose in Pilularia, while they are flattened in Marsilea. The ferns in the genus Pilularia also have lost their leaf blades, with only the grass-like stipe remaining. However, this plant retains the circinate vernation characteristic of most ferns.
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It has many unusual relict characteristics not found in most other Drosera species, including woody rhizomes, operculate pollen, and the lack of circinate vernation in scape growth. All of these factors, combined with molecular data from phylogenetic analysis, contribute to the evidence that D. regia possesses some of the most ancient characteristics within the genus. Some of these are shared with the related Venus flytrap (Dionaea muscipula), which suggests a close evolutionary relationship. The tentacle- covered leaves can capture large prey, such as beetles, moths, and butterflies.
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Leaf bases are closely spaced along the rhizome, which is generally in diameter and rarely branched. The rhizome bears persistent scales, which are linear to slightly lance-shaped, distantly toothed, straight or slightly twisted, and loosely pressed against the surface of the rhizome. Most of them are brown in color, but at least a few will show a thin, dark central stripe, which does not stand out well from the rest of the scale color. The fronds spring up in clusters and emerge as fiddleheads (circinate vernation).
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Reconstruction of the zosterophyll Sawdonia ornata Reconstruction of Zosterophyllum sp. at MUSE - Science Museum in Trento The stems of zosterophylls were either smooth or covered with small spines known as enations, branched dichotomously, and grew at the ends by unrolling, a process known as circinate vernation. The stems had a central vascular column in which the protoxylem was exarch, and the metaxylem developed centripetally. The sporangia were kidney-shaped (reniform), with conspicuous lateral dehiscence and were borne laterally in a fertile zone towards the tips of the branches.
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As the lower parts of the frond expand and toughen up, they begin to photosynthesize, supporting the further growth and expansion of the frond. By photosynthesizing, the frond increases the amount of solute inside the frond, which lowers the internal water gradient and facilitates an increase in volume that forces uncoiling. In the case of many fronds, long hairs or scales provide additional protection to the growing tips before they are fully uncoiled. Circinate vernation may also be observed in the extension of leaflets, in the compound leaves of cycads.
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A few species in the genera Blechnum, Leptopteris, Sadleria and Todea could also be considered tree ferns in a liberal interpretation of the term. Like all ferns, tree ferns reproduce by means of spores developed in sporangia on the undersides of the fronds. Dicksonia antarctica at Kew The fronds of tree ferns are usually very large and multiple-pinnated, but at least one type has entire (undivided) fronds. The fronds of tree ferns also exhibit circinate vernation, meaning the young fronds emerge in coils that uncurl as they grow.
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Circinate vernation (the unfolding of new leaves as fiddleheads) is found throughout the lanosa clade and also in M. wrightii, the most basal member of the alabamensis clade. Most species have round rachises, although early-diverging members of the alabamensis and lanosa clades have rachises deeply grooved on the upper surface and flattened rachises shallowly grooved near the frond tip, respectively. Leaf indument (hairs and scales) is highly diverse across the genus and a key feature in species identification. Myriopteris covillei has large, prominent scales beneath the leaf.
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Detail of a leaf A leaf wrapped around prey Detail of a flower Drosera regia plants are fairly large herbs that produce horizontal woody rhizomes and a crown of large, linear leaves up to long and wide. The leaves possess stalked glands (tentacles) on the upper surface of the lamina along nearly the entire length of the leaf. The leaves lack petioles and stipules, emerging by circinate vernation (uncurling) and tapering to a filiform point. The tentacles and the leaf itself are capable of responding to prey by bending toward insects trapped in the sticky mucilage produced by the glands.
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Drosophyllum ( , rarely ) is a genus of carnivorous plants containing the single species Drosophyllum lusitanicum (Portuguese sundew or dewy pine). In appearance, it is similar to the related genus Drosera (the sundews), and to the much more distantly related Byblis (the rainbow plants). Darwin Drosophyllum lusitanicum is native to the western Mediterranean region (Portugal, Spain and Morocco), and is one of the few carnivorous plants to grow in dry soil. The 20- to 40-cm (8- to 16-in) glandular leaves, which uncoil from a central rosette, lack the power of movement common to most sundews, but have the unusual characteristic of coiling 'outward' when immature (outward circinate vernation).
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The genus Zosterophyllum was erected in 1892 by David P. Penhallow for the type species Zosterophyllum myretonianum, based on fossils found at Myreton quarry near Dundee, Scotland, in Lower Devonian rocks (from about ). Species with radially symmetrical spikes of sporangia have been placed in subgenus Zosterophyllum, those with bilaterally symmetrical spikes in subgenus Platyzosterophyllum. Hao and Xue in 2013 used the absence of terminal sporangia to place some species, such as Z. llanoveranum, in the paraphyletic order Gosslingiales, a group of zosterophylls considered to have indeterminate growth, with fertile branches generally showing circinate vernation (initially curled up). Other species, such as Z. myretonianum, were not placed in the order, as they did not have terminal sporangia.
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