Pteris marquesensis
| Pteris marquesensis | ||||||||||||
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Illustration of Pteris marquesensis |
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| Lorence & KRWood |
Pteris marque sensis is a plant from the genus of pteris within the family of pteridaceae (Pteridaceae). It is known from twoislands belongingto the Marquesas Islands in the South Pacific .
description
Pteris marquesensis is a perennial herbaceous plant . It grows as a large terrestrial fern , i.e. on earth. It forms a short creeping or semi-upright rhizome , which is covered at the ends with scales and has a diameter of up to 2 centimeters. Together with the scaly base of the frond stalks, the rhizome can grow up to 15 centimeters. Often several rhizomes grow next to each other. The uniformly shiny reddish brown scales on the rhizome and the frond base are linear with a length of 15 to 30 millimeters and a width of 0.5 to 0.7 millimeters. The scale margins are almost entire or rarely have short teeth. Between these scales there are also smaller and narrower scales.
At the ends of the rhizome there are four to seven fronds arranged in tufts. The straw-yellow frond stems are 60 to 134 centimeters and 0.4 to 0.6 centimeters thick. The frond stalks are furrowed on the upper side and, especially in the lower third, densely covered with dark brown needle-shaped scales. The upper two thirds of the frond stalks are less densely covered with scales. The scales have almost entire margins and a thread-like tip.
The simply pinnate fronds are 66 to 90 centimeters long and 35 to 64 centimeters wide and are triangular-egg-shaped and have a feathery tip that tapers to a point and a blunt to truncated base. They contain six to ten pairs of parchment-like leaflets. The leaflets are simply pinnate in larger fronds, but unfeathered in smaller fronds. The lowest one to five pairs of leaflets stand on a 2 to 6 millimeter long stalk, are usually irregularly pinnate or lobed towards the base, more rarely also feathered and unlobed. With sterile fronds, they can occasionally be lobed towards the tip. The largest leaflets are also located in the lower area of the frond and are 22 to 36 centimeters long and 11 to 28 centimeters wide. The slightly sickle-like pinnate lobes on the lower side of these leaflets are linear-oblong to linear-triangular with a length of around 13 centimeters and a width of around 2.5 centimeters. The pinnate lobes on the upper side of these leaflets have a pointed or tapered point, which can also be blunt with shorter lobes and are only about half as long as those on the underside. The leaflets in the middle and upper part of the frond sit on the frond stem and have entire margins, whereby these can also be finely sawn towards the tip of the lobe. The leaflet base lies on the upper side of the frond stem while it is free on the underside. The straw-colored central veins of the leaflets are furrowed on the upper side and covered with individual dark brown, needle-shaped scales, which can be up to 2 millimeters long.
The sori are located along the pinnate leaf margins, but are absent at the sawn tips of the leaflets and are covered by an approximately 1 millimeter large indusium with entire margins. The spores are medium brown in color.
Occurrence
Pteris marquesensis occurs on the islands of Hiva Oa and Tahuata , which are part of the Marquesas Islands in the southern Pacific . Pteris marquesensis grows there in damp forests and scrubland which is dominated by Crossostylis biflora , Freycinetia species, Metrosideros collina and Weinmannia marquesana . Cyrtandra species, the noni tree ( Morinda citrifolia ), shrub species ( Psychotria spec.), Vaccinium cereum and numerous other vascular spore plants such as striped ferns ( Asplenium ), Doodia marquesensis and Tmesipteris gracilis and various mosses also occur as socialized species .
Systematics
The first description of Pteris marque sensis was made in 2011 by David H. Lorence and Kenneth Richard Wood in phytokeys , number 4, page 30. The specific epithet marque sensis refers to the Marquesas Islands, on which this type endemic is.
Pteris marquesensis is fundamentally different from all other Pteris species found in Micronesia and Polynesia . The species Pteris warburgii that occurs in Papua New Guinea still shows the greatest similarities with Pteris marquesensis .
swell
- David H. Lorence, Warren L. Wagner, Kenneth R. Wood, Alan R. Smith: New pteridophyte species and combinations from the Marquesas Islands, French Polynesia . In: PhytoKeys . No. 4 , 2011, ISSN 1314-2003 , p. 5-51 , doi : 10.3897 / phytokeys.4.1602 .
Individual evidence
- ↑ a b c d e f g David H. Lorence, Warren L. Wagner, Kenneth R. Wood, Alan R. Smith: New pteridophyte species and combinations from the Marquesas Islands, French Polynesia . In: PhytoKeys . No. 4 , 2011, ISSN 1314-2003 , p. 5-51 , doi : 10.3897 / phytokeys.4.1602 .
- ↑ Pteris marquesensis. In: The International Plant Names Index. www.ipni.org, accessed November 10, 2015 (English).
