Dipteridaceae

Dipteridaceae

▪ plant family
      the umbrella fern family, in the division Pteridophyta (the lower vascular plants (plant)). The family has a long fossil history dating back to the Triassic Period (250 to 200 million years ago), but it presently contains only two extant genera, Dipteris (11 species) and Cheiropleuria (1 species).

      Dipteris includes eight species restricted to moist rocky slopes in tropical and warm-temperate regions from Asia to Australia and three species found from Papua New Guinea to the Solomon Islands (a biogeographical region known as Papuasia). The leaves are very atypical for ferns, with the lamina divided into two primary leaflets or deep lobes, which are more or less fan-shaped and in most species palmately divided into several irregular lobes. The yellow sporangia are clustered into small round naked sori along the network of minor veins between the dichotomously branched main veins. The spores are bean-shaped (bilateral).

      The only extant species in Cheiropleuria is C. bicuspis, which is distributed from East Asia (including Japan) to Malesia (see Malesian subkingdom (biogeographic region)). Its leaves are dimorphic; that is, the fertile leaves have a long narrow entire lamina with the undersurface entirely covered with sporangia, but the vegetative leaves have a much broader lamina that is often deeply notched or two-lobed at the tip. The spores are more or less globose (tetrahedral).

George Yatskievych
 

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Universalium. 2010.

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