Showing papers in "Kew Bulletin in 1978"

Further notes on Cucurbitaceae: IV* Some New-World taxa

Abstract: Summary. The generic taxonomy of the tribes Melothrieae and Sicyoeae is clarified. The generic status of Doyerea and the generic distinctness of Gurania and Psiguria are confirmed. Dieudonnaea is included in Gurania, Frantzia, Polakowskia and Ahzolia in Sechium and Anomalosicyos, Sicyocaulis and Skottsbergiliana in Sicyos. Sechium is divided into Sect. Sechium and the new Sect. Frantzia. Nineteen new combinations, ten new species and one new name are proposed. Lists of accepted taxa studied, and of determinations of numbered exsiccata studied, arranged under countries and collectors, are given. These notes fall into two parts, the first containing general taxonomic comments, new taxa and other taxonomic and nomenclatural changes, the second a list of accepted taxa studied and exsiccata seen, arranged according to countries and collectors. The New-World Cucurbitaceae badly need a thorough taxonomic revision along 'Flora Neotropica' lines, and the present paper is hardly more than a stop-gap pending the undertaking of such an account. Nevertheless, it may be found of value, especially to workers on the crop plants in the family, as indicating the taxa most closely allied to the cultivated species and thus those most likely to be of use in broadening the genetic bases of the crops, and to curators of herbaria, in which numerous specimens are at present undetermined or misidentified. To the many collectors and others who have provided or loaned specimens for study, my gratitude for their indispensable kindness is freely given. Specimens of the new species (other than types) will be given in full in the forthcoming Flora of Venezuela account.

A scanning electron microscope survey of grass pollen

Abstract: wild grass pollen measures 20-30 om in diameter, that of cereals over 35 Fm. Faegri & Iversen (1964) considered 40 Pm to be the dividing line. Bonnefille (1972) pointed out that whilst this distinction works in European grasses, some tropical cereals such as Eragrostis tef and Sorghum have smaller pollen grains than some wild species. This may be due to the fact that these primitive cereals are little differentiated from their related wild species. Bonnefille also found that in general, pollen size of Ethiopian grasses formed a gradient, from Eragrostideae, measuring less than 35 /Im, to Andropogoneae, measuring up to 50 pm in diameter. The range of pollen diameter within each species is sufficient to render the character of little diagnostic value unless the species to be compared are widely separated along the size gradient. In their study of European grass pollen, Faegri & Iversen commented on sexine differences which they separated as 'scabrate', i.e. composed of 'punctae' or single granules, and 'areolate', i.e. composed of 'maculae' or groups of several granules. These differences, seen using a light microscope, were incorporated in their key to grass pollen, using size as the basic dichotomy to separate wild and cereal grasses. Andersen & Bertelsen (1972) employed a scanning electron microscope to study grass pollen and published several pictures in which the sexine differences seen by Faegri & Iversen are clearly illustrated. Grant (1972) used the two types in her S.E.M. study of Zea and Tripsacum. It can be seen from the above survey that so far studies of the sexine pattern of grass pollen have not ranged widely within the family, being mainly centred on the sub-family Poiiideae. In view of this it was considered of interest to expand this aspect of grass pollen to include examples from the majority of tribes.

Crinipellis perniciosa (Agaricales).

Abstract: Crinipellis perniciosa (Stahel) Singer is one of the more serious plant pathogens, being the causal agent of witches' broom disease of cocoa. Distribution is confined to the cocoa areas of lowland tropical South America, with the disease often reaching epidemic levels in Ecuador, Guyana, Surinam, Trinidad and Tobago. It is also recorded from Bolivia, Brazil, Colombia, Grenada and Peru (C.M.I. Distribution Map No. 37, ed. 3, I975). The fungus attacks species of Herrania Goudst and Theobroma L. (Sterculiaceae), although it is not confined to those genera nor is it always parasitic. Desrosiers & Buchwald (1949) reported basidiocarps resembling C. perniciosa on dead lianas, bamboo and unidentified wood in Ecuador, whilst Evans (I977) found typical basidiocarps on both hanging and climbing lianas, fallen debris caught in understorey canopy and on unidentified fallen tree branches on the forest floor. The host is attacked by infection of the breaking vegetative buds, flower-cushions and young fruit. Hyperplasia results and the proliferated growths form the 'witches brooms' which characterize the disease. The disease has been thoroughly reviewed by Baker & Holliday (1957) and Thorold (1975: 11-26). Published descriptions of the agaric basidiocarps are largely confined to the original account given by Stahel (1915: 16), based on material from Surinam, together with additional information on the microcharacters by Singer (1942: 503), following a study of the authentic material. Dennis (1951: 429, pl. 20/4) gave a brief, illustrated account of specimens collected from Theobroma in Trinidad. These accounts were subsequently summarised by Baker & Holliday (1957) and Holliday (1970). Following an extended field investigation of the disease in Ecuador, during 1973-1976, by Dr. H. C. Evans, it has become apparent that the basidiocarps are far more variable than hitherto realized. Constant differences may be recognized in size and pigmentation of the basidiocarp, host range and spore size range. It is decided for these reasons to provide a revised detailed description, recognizing three distinct varieties.

Chlorophytum and its related genera (Liliaceae)

Abstract: Summary. A reappraisal is made of the generic characters used in separating Anthericum, Chlorophytum, Dasystachys, Debesia (Acrospira), Diuranthera, Echeandia, Trachyandra, Trichopetalum (Bottionea) and Verdickia. Debesia is placed under Anthericum. Dasystachys, Diuranthera and Verdickia are all sunk into Chlorophytum. A key to the recognised genera is given and the necessary new combinations and new names are made. Herbarium workers have always found it difficult to distinguish between the genera allied to Chlorophytum. Sometimes one is at a loss to know in which genus to try to name a specimen, especially if seeds are not at hand. The results set out below were obtained from a reappraisal of the characters traditionally used to separate Anthericum L., Chlorophytum Ker-Gawler, Dasystachys Bak., Debesia Kuntze (Acrospira Bak.), Echeandia Ortega, Trachyandra Kunth, Trichopetalum Lindley (Bottionea Colla), and Verdickia De Wild. The re-evaluation was done by using punched cards and the initial survey largely restricted to the East African species. The time available did not allow for a thorough study of all species. We wish to thank the Directors of the herbaria at Geneva (G), Brussels (BR) and Paris (P) for the loan of type material.

A revision of Rhodomyrtus (Myrtaceae).

Abstract: The genus Rhodomyrtus is considered to contain eleven species, distinguished from all other genera in the tribe Myrteae by the fourto five-merous flowers and the seeds separated by false septa in the berry. Rhodamnia salomonensis C. T. White is transferred to Rhodomyrtus; Macropsidium elegans Blume is an older name for Rhodomyrtus calophlebia C. T. White and the necessary new combination is made. Rhodomyrtus sericea Burret is considered to be only a juvenile form of R. trineura F. Muell. ex Benth, while R. novoguineensis Diels and R. canescens C. T. White & Francis are treated as varieties of R. trineura. R. parviflora Alston is also retained as a variety of R. tomentosa (Aiton) Hassk. Two species are excluded: R. recurva C. T. White is transferred to Pilidiostigma and R. beckleri (F. Muell.) L. S. Smith is transferred to Archirhodomyrtus.

Variation in the susceptibility of African Acacia (Leguminosae) to seed beetle attack

Abstract: Summary. This paper is concerned with the apparent infestation anomalies which exist amongst various Acacia species, based on our present knowledge, and the need for further work to highlight the part played by beetles in the ecology of the various species. For those who have not seen either the adults or the damage caused by the larvae it may be useful to describe briefly the life-cycle. In most instances the female selects a ripening pod or, rarely, an already ripened one which has dehisced, and lays an egg, which (depending on the species concerned) is either a round or ovoid flattened structure closely adhering to the surface and held there by a secretion placed over it by the female. Alternatively the egg may be cylindrical and held to the pod by strands of ropelike secretion. The young larva on hatching bores through the pod wall and wanders around until it finds a suitable developing seed. It burrows into this ripening seed and hollows out a chamber, which it enlarges as it grows. When full- grown, it eats away the cotyledon and epidermal layer until a thin circular 'window' of very thin testa is left. The larva then pupates within its feeding chamber and the adult emerges by gnawing at the thin 'window' and pushing its way out. In a few species the full-grown larva leaves the seed and pod through a small circular hole, drops to the ground on a thread of silk and forms a pupal cocoon in the soil under the tree or shrub.

Studies in the Genus Polystachya (Orchidaceae) in Africa

Abstract: The following notes arise from preparation of an account of Polystachya for the Flora of Tropical East Africa. However, I have not confined the accounts to East African specimens alone but, where relevant, have included discussion and revision of material from the rest of Africa and from Madagascar. All the specimens cited have been seen unless indication is given to the contrary; East African specimens are cited in accordance with Flora of Tropical East Africa usage. I would like to thank the Directors of the Paris and Berlin herbaria and the botanist in charge of the East African Herbarium for allowing me to examine relevant material during my recent visits to their institutions.

Hygrocybe sect. Firmae (Agaricales) in Tropical America

Abstract: An illustrated revision is provided of the species of Hygrocybe Kummer with dimorphous basidia which occur in tropical America. Nine taxa are recognized. Hygrocybe chloochlora Pegler & Fiard, H. martinicensis Pegler & Fiard and H. occidentalis var. scarletina Pegler & Fiard are described as new. Hygrocybe hypohaemacta (Corner) Pegler, H. trinitensis (Dennis) Pegler and H. occidentalis (Dennis) Pegler are proposed as new combinations, and H. naranjana Pegler as a nomen novum.