CHROMOSOME COUNTS OF COMPOSITAE FROM THE UNITED STATES AND MEXICO

Chromosome counts are reported for 126 taxa representing 122 species and 61 genera of Compositae. First reports include two genera, Stylocline (n = 14) and Chromolepis (n = 19), 17 species, two infraspecific taxa, and one interspecific hybrid. Five additional taxa have chromosome numbers differing from previously published accounts. Carminatia is reinstated to generic status.     

CHROMOSOME COUNTS OF COMPOSITAE FROM MEXICO AND THE UNITED STATES

Chromosome counts of Compositae are reported from Mexico and the United States. First generic counts are from Egletes (n = 27), Hydropectis (n = 9), and Pippenalia (2n = ca. 60). First counts also are reported for 22 specific and infraspecific taxa in Baccharis, Erigeron, Flaveria, Gnaphalium, Grindelia, Helenium, Heterotheca, Melampodium, Montanoa, Perymenium, Piqueria, Senecio, Stevia, Verbesina, Xanthocephalum, and Zaluzania. Additional counts also are provided for 123 populations of taxa counted previously, of which eight are new numbers. Taxonomic implications of certain counts are discussed.     

CHROMOSOME COUNTS AND TAXONOMIC NOTES FOR COMPOSITAE FROM THE UNITED STATES AND MEXICO

Chromosome counts are reported for 167 taxa representing 160 species and 76 genera of Compositae. First reports for 27 species and 2 infraspecific taxa are included. New chromosome numbers are reported for 9 additional taxa. The genus Carminatia DC. is merged with Brickellia Ell. resulting in two new combinations: Brickellia tenuiflora (DC.) Keil & Pinkava and Brickellia recondita (McVaugh) Keil & Pinkava.     

CHROMOSOME STUDIES IN ASTERACEAE FROM THE UNITED STATES,MEXICO, THE WEST INDIES,AND SOUTH AMERICA

Chromosome counts of Asteraceae are reported from Mexico, the United States, the West Indies, Peru, and Bolivia. First counts are reported for 27 species, eight infraspecific taxa, and three interspecific hybrids in Brickellia, Chrysanthellum, Cirsium, Egletes, Erigeron, Flaveria, Gnaphalium, Heterotheca, Hieracium, Hymenothrix, Koanophyllon, Layia, Lessingia, Pectis, Sclerocarpus, Stuessya, Tagetes and Wedelia. Counts are also reported for 196 taxa or hybrids for which chromosome numbers have been published previously. Of these, nine are new numbers. Taxonomic implications of certain counts are discussed.     

CINEMATIC OBSERVATIONS ON THE GROWTH AND DIVISION OF CHLOROPLASTS IN NITELLA

As it elongates from about 0.2 to 80 mm, the Nitella internodal cell shows an increase in plastid number from a few thousand to about 4 million. The increase takes place by plastid division. A continuous motion picture record followed a population of 8 plastids in an elongating cell until their progeny numbered 18, a span longer than 1 fission cycle for some of the plastids. One complete fission-fission cycle was about 22 hr. The highly directed nature of chloroplast expansion (elongation) is lost when cell wall strain (expansion) is mechanically inhibited by pressing the cell between glass plates. The plastids then expand about equally in all directions in the plane of the cell surface. When a new direction of maximum strain is introduced by the mechanical induction of a lateral in the cell, the plastids elongate in this new direction. The direction of the protoplasmic stream does not show this striking response to strain but tends to follow the lines of the chloroplast chains, not the long axis of individual plastids.     

ACACIA CONSTRICTA (FABACEAE: MIMOSOIDEAE) AND RELATED SPECIES FROM THE SOUTHWESTERN U.S. AND MEXICO

Vegetative, fruit, and floral characters of more than 200 herbarium specimens of Acacia constricta and closely related species from the Southwestern U.S. and Mexico were scored and analyzed by principal components analysis (PCA) and stepwise discriminant analysis (SDA). The results show that all of the 5 species of this group are distinct and form nonoverlapping groups in plots of the first three principal components. All taxa were found to be quite homogeneous as indicated by the tight clusters formed in the PCA plots. Acacia pacensis, whose relationship to the species of this group has been questioned, is confirmed to be more closely related to A. farnesiana and related species. Some specimens with a combination of characters from A. constricta, A. neovernicosa, and A. schottii were positioned intermediate to the putative parental species groups in the PCA and SDA plots, suggesting hybridization among these taxa.     

OBSERVATIONS ON ORGANIC VOLATILES FROM GERMINATING SEEDS AND SEEDLINGS

Germinating seeds of several plant species evolved oxidizable volatile compounds, including aliphatic aldehydes. Formaldehyde comprised only a small percentage of the total aldehydes detected. Most seeds evolved these compounds only during the first three or four days after imbibition, with peak production occurring during the second day. In general, larger seeds evolved greater quantities than smaller seeds, but, on a unit weight basis, smaller seeds evolved more. Dry, non-germinating, or killed seeds evolved little or no volatiles, indicating that active seed metabolism was required for the production of volatiles. The light-dark regime appeared to have little effect on volatile evolution.     

THE DISCOLORATION OF ROOFS IN THE UNITED STATES AND CANADA BY ALGAE1

Roof shingles are often colonized and discolored by blue-green and green algae. The former are mostly subaerial species and the latter are soil algae most frequently recovered from the atmosphere.     

VIABILITY OF SEEDS UP TO 211 YEARS OLD EXTRACTED FROM ADOBE BRICK BUILDINGS OF CALIFORNIA AND NORTHERN MEXICO

Seeds recovered from adobe walls of historic buildings in California and Northern Mexico were assayed for viability and germinability. Seven of the approximately 40 species tested had one or more viable seeds. These were (age of seeds in parentheses) Medicago polymorpha (200), Malva parviflora (200, 195, 183), Hordeum leporinum (200), Trifolium sp. (193), Melilotus indicus (183), Chenopodium murale (183), and C. album (143). Additionally, 41-yr-old seeds of Lotus corniculatus collected from living plants were found to be viable. Seeds of Medicago polymorpha and Lotus corniculatus germinated and produced normal seedlings. The importance of seed longevity in weedy species is briefly discussed.     

新疆、青海和四川等地区小麦族植物的细胞学观察

本文对采集于新疆、青海和四川等地的小麦族(Triticeae Dumortier)10属、52种、370份种子材料进行了细胞学观察。该地区小麦族各属种的染色体数目变化范围是从2n=14到2n=84,前者主要存在于大麦属(Hordeum)、新麦草属(Psathyrostachys)和黑麦属(Secale),而后者全部集中于赖草属(Leymus)。其中染色体数目为2n=28和2n=42的类型出现的频率很高,大多存在于鹅观草属(Roegneria)和披碱草属(Elymus)。除个别种内存在不同倍性的细胞型外,绝大多数种的染色体数目非常稳定。在所有的样本中均没有观察到具非整倍体和B-染色体的材料。     

PHOTOPERIOD IN XANTHIUM POPULATIONS FROM TEXAS AND MEXICO

Photoperiodic responses of Xanthium strumarium L. originating between 19° N in Mexico and 34° N in Texas varied among seedlings grown from seed under controlled conditions. The critical night lengths form a gradient from 9.5 hr in northern Texas to 10.75 hr in southern Texas and northeastern Mexico. Populations with critical night lengths of 9.5 and 9.75 hr showed a longer interval to flower bud formation under cooler temperatures (24 C day/15 C night) than under warmer temperatures (30 C day/24 C night). Three of four populations with a 10.75-hr critical night length showed a shorter interval under the cooler temperature regime. Although the Texas populations demonstrate a strong correlation of photoperiodic response with latitude, the Mexico populations show diverse photoperiodic timing from approximately the same latitude. The study emphasizes that a combination of critical night length and ripeness-to-flower (maturity) response forms the basis for reproductive adaptation in different climatic regimes in Texas and Mexico.     

OBSERVATIONS ON THE GREATER KUDU TRAGELAPHUS STREPSICEROS PALLAS FROM A TSETSE CONTROL HUNTING SCHEME IN NORTHERN RHODESIA

Material from kudu shot on tsetse control was studied for information on breeding and feeding habits. A number of animals was measured and weighed, illustrating that males were bigger than females.
Field observations and stomach contents showed that the species is mainly a browser eating a wide variety of plants.
A marked peak of calving was observed and this coincided with the tall grass season (January-April), when the newly-born young are apparently hidden. Kudu in the area studied may be solitary but are generally associated in small groups of about four, although as many as eleven have been seen together in the study area.     

OBSERVATIONS ON THE BREEDING OF THE PIED CROW AND GREAT SPOTTED CUCKOO IN NORTHERN NIGERIA

Mundy. P. J. & Cook, A. W. 1977. Observations on the breeding of the Pied Crow and Great Spotted Cuckoo in northern Nigeria. Ostrich 48:72-84.

The breeding cycle of the Pied Crow Corvus albus was studied in 1971. The birds bred in the wet season and all of 23 pairs were single-brooded. They appeared to nest territorially, and mostly close to human habitations. Average clutch size was 4.8 eggs and the greenish eggs were either pale and lightly marked, or darker and heavily marked. The average incubation and fledging periods were 181/2 and 38 days respectively. Chicks hatched asynchronously. Five crow nests were found parasitised by the Great Spotted Cuckoo Clamator glandarius and it appeared that only one hen cuckoo was responsible. The cuckoo apparently did not remove, or even crack, host eggs. One instance of an adult cuckoo feeding a juvenile was seen. In terms of growth increments a cuckoo chick substituted for one-half a crow chick but developed faster and fledged in nearly one-half the time. The cuckoo reduced host breeding success practically to zero apparently by indirect means, which contrasts with its situation in Europe.     

OBSERVATIONS ON THE SLATY EGRET EGRETTA VINACEIGULA IN NORTHERN NAMIBIA

Hines, C.J.H. 1992. Observations on the Slaty Egret Egretta vinaceigula in northern Namibia. Ostrich 63: 118–122.

The Slaty Egret is an endemic African resident with a limited distribution in Botswana, Zambia and Namibia. Distribution records for Namibia are reviewed and information on movements and habitat preferences is given. Diet and feeding habits are described. Two colonies of Slaty Egrets containing eggs and chicks were found on temporary wetlands in eastern Bushmanland. Nests and eggs are described and egg measurements and weights given. The plumage of immature birds is described as well as the variation in adult plumages. The conservation status of the species is reviewed, and the possible importance of temporary wetlands to the Slaty Egret is discussed.     

OBSERVATIONS ON THE ECOLOGY OF LAMINARIA SINCLAIRII ON THREE NORTHERN OREGON BEACHES1,2

Laminaria sinclairii (Harvey) Furlow, Anderson and Eaton occurs only on the Pacific Coast, of North America and is usually restricted to rocks on beaches subjected, to moderate to heavy surf and a large seasonal fluctuation in sand level. It was observed and measured over a 2-year period-on 3 such beaches in northern Oregon. Growth, rate and, relative dominance are greatest in the lowest and most exposed parts of the inter tidal zone, where surf action and sand burial are greatest. The sand level begins to build up on the beach in April and continues to rise, burying the plants, throughout the summer, until the first, heavy storms in fall again remove the sand. Maximum growth occurs in early summer, prior to burial. The blades are lost in December and regenerated in January. Ripe sori are produced on the old blades just before they are lost and on the new blades just after they appear. The gametophyles which, develop from spores produced by these sori apparently do not usually produce sporophytes. In March and April there is considerable production of new stipes and blades from the haptera at the margins of the holdfast and this is apparently the chief means of reproduction.