Σάββατο, 26 Νοεμβρίου 2011

Matteuccia struthiopteris

 (L.) Todaro

Ostrich fern

Etymology Struthiopteris, Latin, from struthio, ostrich, + pteris, Greek, from pteron, a wing, referring to the shape of the pinnae, but the word pteris was used by the ancient Greeks for ferns in general.
Description Rhizome: erect, forming a vase-like plant, becoming short trunks with age, armoured with black, old stipe bases, appearing braided.
Frond: 150 cm high by 30 cm wide, sterile: deciduous, late-appearing; fertile: appearing midsummer, persisting into winter, infrequently produced, dimorphic, the fertile frond to 40 cm x 6 cm, blade/stipe ratio: 5:1.
Stipe: green, with an expanded base (trophopod), white hairs on sterile frond, also orange-brown scales, vascular bundles: 2, s-shaped, back-to-back, at an acute angle.
Blade: sterile: 1-pinnate-pinnatifid, elliptic, widest one-quarter below apex, abruptly reduced towards the tip, sterile: herbaceous, fertile beady, green young, maturing to dark brown, absent or deciduously hairy below.
Pinnae: 20 to 60 pair, proximal pinnae (several pairs) greatly reduced, sessile; pinnules oblong, blunt, 20--40 pairs per pinna; costae shallowly grooved above, grooves not continuous from rachis to costae; margins entire; veins free.
Sori: round, covered by revolute margins, indusium: vestigial, sporangia: green, maturity: the following spring.

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