Gametophytes of the fern family Thelypteridaceae were cultivated aseptically under controlled conditions and investigated with the scanning electron microscope. This report concerns six species, viz. Sphaerostephanos arbuscula S. subtruncatus, S. unitus, Macrothelypteris torresiana, Amauropelta hakgalensis and Pneumatopteris truncata. The gametophytes have some features in common. They are more or less heart‐shaped and have glandular trichomes on surfaces and margins. In the middle is an elongated cushion bearing gametangia and rhizoids on the lower surface. Antheridia are of the type common to leptosporangiates, consisting of a basal cell, a ring cell and a cap cell. Archegonia consist externally of four rows of cells meeting at the top with triangular cells. The following features are distinguishing. The form of the margin of the thallus, type of hairiness, and the abundance of glandular hairs. Acicular hairs occur in Sphaerostephanos unitus and Pneumatopteris truncata. In Amauropelta hakgalensis the archegonium deviates from the common type in having a basal layer that consists of eight cells instead of four. In Macrothelypteris torresiana the four or three top cells are markedly irregular. In Sphaerostephanos arbuscula and Amauropelta hakgalensis the antheridial cap cell is sometimes divided. The manner of opening of antheridia and release of spermatozoids varies in each of the species investigated. This investigation reveals that it is possible to identify the species from gametophyte characters only.
Tigerschiold, E. 1990. Gametophytes of some Ceylonese species of Thelypteridaceae.-Nord. J. Bot. 9: 657-664. Copenhagen. ISSN 0107-055X.Gametophytes of 12 species of the family Thelypteridaceae were investigated with Cryo-SEM and conventional SEM. Most of the species have rounded front lobes and rounded lobes extending backwards. Metathelypteris flaccida has a cordate gametophyte. All species have glandular hairs, which are of different length and could be used as diagnostic character in some cases. In addition 7 of the species investigated have acicular hairs. In Thelypteris confluens the glandular hairs on margins and surfaces are born on cells that protrude from the surrounding cells. It is concluded that the combination of characters makes it possible to distinguish species of different genera with the help of gametophyte characters only.
Tigerschiold, E. 1989. Dehiscence of antheridia in thelyptheroid ferns. -Nord. J. Bot. 9: 407412. Copenhagen. ISSN 0107-055X.The manner of antheridial opening was investigated in 18 species of the family Thelypteridaceae by scanning electron microscopy. Four different types have been observed: 1) An irregular rupture in the cap cell wall. 2) A rounded opening like a pore.3) The cap cell being totally thrown off. 4) Opening at one side like a lid, with the cap cell still being attached to the ring cell on the opposite side. Although it has been claimed that the manner of dehiscence is specific to different species, no evidence for this view was found. In 9 of the 18 species studied at least two manners of opening occurred. In 7 of the 18, three or four occurred. In the majority of cases male gametes are in the spermatid stage at time of release from the antheridium. Later on the slimed cell wall dissolves and the spermatozoids are liberated. In a few cases this process is more or less completed within the antheridia, so that spermatozoids are mature already at the time of release.
An investigation of the Asplenium trichomanes complex in some Swedish provinces is presented. The study comprises ssp. trichomanes 2n = 72, ssp. inexpectans 2n = 72, ssp. quadrivalens 2n = 144 and a triploid hybrid 2n = 108. The ssp. inexpectans is reported from Sweden for the first time. It is previously only known from Central and Southern Europe. It was found to be about as common as the other two subspecies occurring in Sweden.
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