Arizona Plants Research Articles

Essential Oil Plants of Southern Arizona

Examination of thirty-five species of southern Arizona plants for their steam-volatile oil content is reported. Fresh-weight yields from 0.01 to 0.9 per cent were obtained. Based on the physical and chemical properties of the extract, Dalea lumholtzii contained up to 78 per cent of oxygenated terpenes, Lippia wrightii showed about 80 per cent of terpene hydrocarbons, while other plants yielded values ranging between these two extremes.

New Arizona Plant Records

New Arizona Plant Records

A Study of the External Surface of Opuntia Imbricata (Haworth) DC

A comparative study was made of the subterranean and aerial por- tions of 0. imbricata. This plant had a fibrous root system which branched out into the quaternary division. Roots of both tertiary and quaternary divisions were fairly well covered with hairs. The surface area of the tops exceeded the subterranean sur- face by about 3:1. Stomates in the epidermal surface of the canes numbered 11 per sq. mm. The purpose of this investigation was to gain a better understanding of a very successful species living in an arid environment. Most of the work on desert plants has been concentrated on aerial portions and the various modifications of these plants to endure the dessicating winds, intense heat, sparse rainfall, and infertile soils characteristic of these regions. In 1911 Cannon wrote extensively of the rooting habits of desert plants in Arizona. His descriptions were confined mainly to the major roots and did not include detailed surface relationships. Since that time several papers have appeared with data on the root systems of various plants. Much of Weaver's work (1925; 1926) dealt with the root systems of crop and field plants and also grasses of the Great Plains. Included in the 1925 investigation was an estimate that root surface area exceeded the top by 35 per cent. Observations by other investigators have resulted in similar opinions, although no de- tailed study of complete surface relationships were available until Dittmer (1937) described the external surfaces of a winter rye plant. Earlier studies by Kiesselbach (1910) reported the dry weight of the tops of corn to be 7.2 times that of the roots and Pavlychenko (1937) described the entire root system of crested wheat, but complete studies showing the surface relationships of individual plants have been few. Usually one worker has described the root system of a plant or a species and another described the tops. Even though the figures may not have been of the same species and certainly not the same plant, a third investigator often attempted to correlate these results. In this paper the writer presents complete figures for a single xeric plant.

Notes on Arizona Plants

Records are cited for the following: Charophycophyta-Characeae: Chara contraria A. Br. (Maricopa Co.), C. zeylandica Klein (with preceding), C. globularis Thuill. (Apache Co., Navajo Co.), Nitella sp. Angiospermae-Najadaceae: Najas marina L. (Maricopa Co.), Hydrocharitaceae: Vallisneria americana Michx. (Maricopa Co., new to Arizona). Gentianaceae: Menyanthes trifoliata L. (Apache Co.; new to Arizona). Recent Arizona plant collections have revealed the existence of two species not previously recorded for the state, and noteworthy range extensions of several others. Specimens of the following are in the herbarium of Arizona State College, Tempe. Collections were made by the writer unless otherwise stated.

Notes on Grimmia orbicularis Bruch

omit it from their list, published in 1892,2 but it is mentioned by Cardot, in 19I I, as follows: orbicularis Bruch.-District federal Mexico (Wagner; herb. C. Warnstorf). Europe, Asie, Afrique mediterraneenne, region magellanique., which is the only available reference to the plant in the Western Hemisphere. In view of the above facts it is interesting to record G. orbicularis as one of the characteristic species of the moss flora of Southern Arizona. It grows abundantly, at altitudes below 2500 ft., on ledgy steep banks of dry washes within a radius of fifty miles from Tucson, where the deep broad black-green mats contrast strongly with the smaller grey-green cushions of Grimmia pulvinata. The field distinctions are so obvious and unmistakable ihn this limited area that it is hard to understand how such a representative species as G. orbicularis has hitherto escaped detection. It is reasonable to suppose that it ranges more widely through the Lower Sonoran Zone and down along the west coast of Mexico, but our meager knowledge of the moss flora of these arid southwestern regions confines this to a mere supposition. Through the courtesy of Mr. E. B. Chamberlain, it has been possible to make detailed comparisons with European exsiccati, and similar comparisons very kindly made by Dr. H. N. Dixon indicate that the agreement between our Arizona plants and G. orbicularis of Europe is essentially complete. Apart from the field characters mentioned above, the more minute distinctions of cucullate calyptra, unistratose lamina, and elongated median basal leaf-cells separate this plant clearly from Grimmia pulvinata, the only other species with which it might be confused. BUSHKILL, PIKE COUNTY, PA.

Economy of Certain Arizona Steam-Electric Power Plants Using Oil Fuel

Abstract In certain steam-electric power plants the combination of load factor and high fuel cost not only necessitates but also makes possible the attainment of high economies in operation. These particular conditions exist in three Arizona plants known and located as follows: Inspiration Consolidated Copper Company, Inspiration, Ariz.; New Cornelia Copper Company, Ajo, Ariz. and Arizona Power Company, Clarkdale, Ariz. All of these plants embody many similar features and in this paper the author discusses the economy of operation of each. Tables and curves of operating characteristics are also given and these show that the best economy per bbl. of oil obtained at the Inspiration Plant was 294.5 kw-hr., at the New Cornelia Plant 326.2 kw-hr., and at the Arizona plant 333.3 kw-hr. All these values were obtained during the winter months when conditions were most favorable. The paper concludes with a section dealing with the personnel responsible for the installations.