ALBERT

Description: Er bestaat op het ogenblik de neiging de kleine waterweegbree Baldellia ranunculoides (L.) Parl. te noemen in plaats van Echinodorus ranunculoides (L.) Engelm. In de nieuwste druk van de flora van Heukels-van Ooststroom werd deze naam in de Nederlandse literatuur geïntroduceerd. In mijn Alismataoeae-bewerking voor de Flora Malesiana (1957) heb ik de naam reeds afgewezen, doch een nadere argumentatie zal de Nederlandse floristen stellig interesseren. In 1854 heeft Parlatore Schinodorus ranunculoides als het type van een nieuw monotypisch genus Baldellia aangevoerd, doch hij werd niet nagevolgd. Volgens Pichon (1946) is er evenwel alle reden voor om dit wel te doen, want hij meende niet minder dan 4 kenmerken gevonden te hebben, waarin E. ranunculoides van de andere Echinodorus-soorten zou afwijken.

Description: Annual or perennial aquatics and marsh plants, sometimes laticiferous. Leaves basal and erect, sometimes floating, rarely all submerged, sometimes some reduced to phyllodes, lanceolate to sagittate, rarely broad-elliptic to ovate, entire, with a hydathode on the apex, curvinerved, nerves more or less parallel and gradually joining the marginal nerve, connected by ascending cross-veins; petiole sheathing, mostly with air-channels, often septated. Inflorescences mostly erect, racemose or paniculate; peduncle sometimes hollow, mostly with air-channels. Bracts 3(-2) per whorl of flowers or branches. Flowers actinomorphous, bisexual or unisexual (and then rarely with rudiments of the other sex). Sepals 3, imbricate, green, parallel-nerved, convex, persistent. Petals 3, imbricate, white or faintly coloured, marcescent. Stamens 3-~, free, in a whorl; filaments filiform or dilated; anthers 2-celled, basifix, sometimes versatile, latrorsely lengthwise dehiscent. Carpels 2-~, free, in the Mal. spp. spirally arranged on the receptacle (in extra-Mal. Alisma in a whorl); style 1, ventrally or terminally inserted on each carpel, persistent. Ovule 1 (in extra-Mal. Damasonium 2 or more), basal, campylotropous, rarely anatropous (Damasonium), micropyle extrorse, rarely introrse ( Luronium). Achenes in a head (or whorl in Alisma), free, rarely connate at the base. Seeds oblong or horseshoeshaped; testa membranous; embryo horseshoe-shaped; albumen 0; radicula extrorse, rarely introrse (Luronium). Distribution. About 10 genera with c. 70 spp., all over the temperate and tropical zones except in the Pacific area (Micronesia, Melanesia, and Polynesia). The largest genera are Sagittaria and Echinodorus both centering in the New World.

Description: Since Hornemann (Fl. Dan. 9, 1816, p. 3, pl. 1501) published the name Zostera marina var. angustifolia together with a very poor drawing and the extremely short diagnosis ‘foliis subenerviis’ several interpretations of the identity of this taxon have been given. Some authors regarded it as a separate species closely related to Z. marina L., e.g. Reichenbach (1c. Fl. Germ. 7,1845, p. 3, as Z. angustifolia), and Tutin (J. Bot. 74, 1936, p. 227—230, as Z. hornemanniana). Others thought that it was a hybrid between Z. marina and Z. noltii Hornem., e.g. Ascherson (in Boissier, Fl. Orient. 5, 1882, p. 25), Prahl (Krit. Fl. Schlesw.- Holst. 2, 1890, p. 211), and Rouy (Fl. Fr. 13, 1912, p. 290, as Z. hornemanni). Recently I myself expressed the opinion that Hornemann’s variety was merely a brackish-water form of Z. noltit (Den Hartog, Sea-grasses of the world, 1970, p. 68). Thanks to the kindness of Mr. A. Hansen I was able to study two sheets of original material of Hornemann’s taxon and as a result all the above-mentioned interpretations can be ruled out. One of the two sheets is marked ‘cotypus’ and is labelled ‘Zostera marina angustifolia, e sinu Othiniensi, Hornemann’, the labelling in the characteristic handwriting of Prof. J. W. Hornemann himself. The specimens mounted on this sheet are all extremely narrow-leaved Z. marina. The specimens on the other sheet are very similar, and were collected from the same place; the labelling, however, is in the handwriting of N. Hofmann Bang, who was a close friend of Hornemann and owned the manor Hofmannsgave near the type locality.

Description: The three families of sea-grasses are treated together here, with a general introduction by Den Hartog and a key to the sea-grass genera. An extensive chapter on phytochemistry by R. Hegnauer (Leiden) has been included. Potamogetonaceae, pp. 174—196. The family comprises 3 genera and c. 80 species all over the world, of which in Malesia: Potamogeton (13 species) and Ruppia (1). The general part of the treatment covers c. 5 pages and includes a paragraph on pollen morphology by R.W.J.M. van der Ham (Leiden). Family, genera, and species are described and annotated. There are keys to the genera and species. Zosteraceae, pp. 197-200. The family consists of 3 genera and 17 species, of which only one genus (Zostera) with one species in Malesia. The general part of the treatment covers almost 2 pages and includes a paragraph on pollen morphology by R.W.J.M. van der Ham (Leiden). Family, genus, and species are described and annotated. Cymodoceaceae, pp. 201—216. The family comprises 4 genera and 14 species, mainly in tropical seas, of which in Malesia: Cymodocea (2 species), Halodule (2), and Syringodium (1). The general part of the treatment covers almost 2 pages and includes a paragraph on pollen morphology by R.W.J.M. van der Ham (Leiden). Family, genera, and species are described and annotated. There are keys to the genera and species.

Description: Among water-plant material received on loan from the Western Australian Herbarium, South Perth, there was a very remarkable Nymphaeacea which did not fit in any of the 8 genera so far described in this family. Mr. R. C. Royce, the curator of the herbarium mentioned above, kindly gave his permission for me to work out this material. Fortimately, additional specimens of this taxon were received on loan from C.S.I.R.O., Canberra, through the kind collaboration of Miss Dr. N. T. Burbidge. Dr. R. C. Bakhuizen van den Brink, Leiden, rendered the diagnosis into Latin. Miss R. van Crevel prepared the drawing. Mr. J. Muller studied the pollen of the plant; his findings are given in an appendix to this paper.

Description: The dioecious species of the genus Blyxa can be divided into 2 groups, those with 6 stamens and those with 9 stamens in the male flowers. The first group is restricted to tropical Africa and needs further study. The second group occurs in Asia and Australia and up to now was considered to consist of 2 very distinct species, Blyxa octandra (Roxb.) Planch, ex Thw., characterized by a basal rosette of long, smooth, linear leaves, and B. novoguineensis den Hartog which is caulescent with short serrulate leaves. B. octandra is widely distributed in India, Burma, Indo-China, New Guinea, and the tropical part of Australia. B. novoguineensis is known with certainty only from New Guinea. Recently a third species, very similar in its habit to B. octandra, was found by Dr. C. F. van Beusekom and Mr. R. Geesink in Thailand. From a study of herbarium material it appeared that this species had already been collected several times but had not been recognized as a separate species, probably because of the absence of seeds in these plants.

Description: Halophila stipulacea (Forsk.) Aschers. is a sea-grass which is widely distributed along the coasts of the western Indian Ocean and the Red Sea. In 1895 Fritsch (Verh. Zool. Bot. Ges. Wien 45, 1895, p. 104) recorded the species from the Island of Rhodos in the Aegean Sea. This was the first record of the species from the Mediterranean. There can be no doubt that it penetrated the Mediterranean via the Suez Canal, which was completed in 1869. Although there are no early records of its occurrence in the Suez Canal, it is significant that it was the only sea-grass found during the exploration of the canal by Munro Fox in the autumn of 1924; at that time it was abundant in several localities in the canal. Forti’s record (Nuov. Giorn. Bot. Ital. 34, 1927, p. 714—716) of the species is the second for the Mediterranean; he reported it as being not uncommon in the Dodecanesos. I myself have seen specimens that were collected on Samos in 1924 and near Cape Matapan in 1955 (Den Hartog, Sea-grasses of the world, 1970, p. 260). In spite of the fact that the number of published records is still scanty, it is obvious that H. stipulacea is now well established in the Aegean waters. Further the species has expanded its Mediterranean area considerably, as is apparent from recent records from Malta (Lanfranco, The Maltese Naturalist I, 1970, 16—17, stencilled) and Cyprus. MALTA. Marsaxlokk harbour on the SE. coast of Malta, on rather muddy bottom, quite plentiful, 1-8-1970: G. Lanfranco 1615 (BM, L); ibidem, 5-8-1970: E. Lanfranco 1617, 1618,♂ flowers (L). GREECE. Rhodos. Lindos, Paulus Bay, at 2 m depth, 25-4-1970: Van Steenis (L). CYPRUS. Famagusta, inner harbour near Nisitou Jieri, in shallow water, 23-3-1970: A. Hansen 716 (C, L).

Description: The family Lemnaceae is divided into 2 subfamilies, Lemnoideae with the genera Spirodela and Lemna — the latter with 2 subgenera, Lemna and Staurogeton — and Wolffioideae with the genera Wolffia, Wolffiopsis, Wolffiella, and Pseudowolffia, the last two being new and based on former infrageneric taxa. All these taxa are described, and their types indicated; keys are provided for their distinction. Recognized species names are listed with their synonyms, a few being newly reduced. There are 5 new specific combinations. A list of invalid and dubious names is added. The excluded names are listed separately. An explanatory glossary is given of the terminology used in the descriptions, and is illustrated by some diagrams (fig. 1).