Polypodium interjectum

Common name: Intermediate Polypody
Scientific name: Polypodium interjectum
Genus: Polypodium 多足蕨屬
Family: Polypodiaceae 水龍骨科, polypody family

Remarks: It is an ancient hybrid between Polypodium vulgare 歐亞多足蕨, Polypody and Polypodium cambricum, Southern Polypody. The species is a hexaploid with six sets of chromosomes; each set has 37 chromosomes, giving a total of 222 altogether. Because it is a hybrid it is intermediate in both form and habitat, with some plants being easily mistaken for either of the two parent species. Examination of the sporangia under a microscope is usually required for accurate identification. (From "Flora of Northern Ireland")

Note: As the frond of Polypodium interjectum is very variable. The identity of the following photos could not be confirmed unless the numbers of indurated cells of annulus and basal cells of the sporangium could be counted under a powerful magnifying lens or microscope. However, the oval-lanceolate shape of the frond and the location it is located, i.e. the coastal sand dunes, make it likely the Polypodium interjectum.

Origin: native

Date: 9th Aug

093 Found in coastal sand dune.

105 Another cluster, also present in sand dune.

094 Frond ovate-lanceolate.

096  Frond ovate-lanceolate, longest pinnae 1/3 to 1/2 distance from base. Lowest pair of pinnae slightly reflexed.

102 The tip of the frond, rounded or tapered to tip.

104 The underside of the frond.

104-1 The close-up of the underside of pinnae showing the veination. 

099 The underside of the frond with sori.

99-1 Close-up showing the sporangium with the pale brown annulus.

101 Frond with mature sporangium.