1942: Botany

Plants Bottlenecked by the War.

In the year 1942, the first year 'after Pearl Harbor,' there have been, as a direct result of the war, drastic curtailments in supplies of many essential materials, some of which are dependent for their continued production on plant science in some of its branches, e.g., agriculture, forestry, horticulture; and for the development of new sources, on taxonomy, ecology, anatomy, genetics, etc.

Rubber.

The most important of these materials perhaps is rubber. At the present time about 9/10 of this country's supply of crude rubber, derived mainly from Hevea brasiliensis, a tree member of the spurge family or Euphorbiaceae, has been bottlenecked by the war. Hence there is an urgent need for substitutes, which our scientists, plant and otherwise, have been busily investigating. Guayule, Parthenium argentatum, a small shrub of the composite or sunflower family, is one of those substitutes which can be grown readily in the southwestern United States, where it is in fact native, and grows naturally also in northern Mexico. The President's rubber survey committee, headed by Bernard M. Baruch, has stated that guayule is the principal source of natural rubber that could not be lost to us short of conquest of American territory. Officials of the Forest Service (which has carried on the program of seed collecting and planting) stated recently that 'domestic production in California should amount to 600 tons this winter from mature shrubs previously reserved for seed production.' It is expected to step up sharply to 33,000 tons in the winter of 1944-45, and to 47,000 more tons the following year. Another possible source is the Russian dandelion, Taraxacum Kok-saghyz, also a member of the sunflower family, experimental plantings of which are being made. Synthetic rubbers, for some of which advantages over natural rubber are claimed, are also being manufactured and used by various large rubber concerns, which in some cases had already been working in these products for many years. It should be noted, further, that 2,500,000 plants of Hevea have recently been planted in Haiti where at least 100,000 acres are available for a nearby supply. Also, investigators in the Department of Agriculture are working on a process for the transformation of soybean meal into rubber.

Sugar.

Confronted with a sugar shortage, a larger acreage is being planted to sugar beets, and a new method of seed preparation has been developed for beet 'seed' (strictly a fruit containing several seeds). The production of sorghum for sweetening and of maple sugar is being stepped up. Honey is taking on added significance as a sugar substitute.

Cork.

Experiments in planting cork oak, Quercus suber, from which commercial cork is obtained, are planned by the U. S. Dept. of Agriculture, if acorns can be obtained from the Mediterranean countries. Normally this country imports about $10,000,000 worth of cork each year from Spain, Portugal, and North Africa. Texas, New Mexico, Arizona, and southern California have a climate similar to that of these countries, and the cork oak should grow well in these states.

Drug Plants.

Prof. W. J. Bonisteel, of Fordham University, states that four of the most important drug plants, namely digitalis, belladonna, stramonium and henbane could be raised in sufficient quantity in 1,000 acres to supply all United States needs. Some of the other drug plants that can be satisfactorily grown in this country or elsewhere in the hemisphere include castor oil beans, ginger, orris root, citronella, henna, ergot, and members of the anise-dill-fennel group.

Spray Materials.

As regards the shortage of spray materials for insecticides and fungicides, Neely Turner and James G. Horsfall at the Connecticut Agricultural Experiment Station at New Haven state that 'the means for saving spray materials are legion. Perhaps the most important of these are (1) to use them in troubles that can be controlled, (2) to treat only plants that are likely to be most in need, (3) to improve the efficiency of distribution over the plants, and (4) to give careful attention to the dosages.' These investigators recommend various chemicals which for certain purposes can replace copper, mercury and formaldehyde.

Researches in 1942.

The trend of former years, away from taxonomic and morphological studies of plants, has been maintained. The majority of researches continue to deal with the physiology of plants, i.e., how they behave, or respond, both normally and under special conditions of environment.

Physiological Studies.

Fritz Wendt of the California Institute of Technology, working mainly with tomatoes, finds that, for 'setting' their fruit, they need the alternating light and darkness of day and night, together with concomitant diurnal rise and fall of temperature. This phenomenon has been termed 'thermo-periodism.'

J. V. Overbeek, Marie E. Conklin, and A. F. Blakeslee of the California Institute of Technology at Pasadena and of the Department of Genetics of the Carnegie Institute of Washington, at Cold Spring Harbor, N. Y., have grown young embryos of Datura in vitro for a considerable period, using an agar medium containing dextrose, mineral salts, a mixture of physiologically active substances, plus coconut milk. In one case, after 10 days in the medium, the embryo had increased 8,000 times in volume. Viable seedlings were obtained by transferring these 'incubated' embryos, after one week, to a medium without coconut milk, since the latter was found to inhibit root growth. Roots then developed and viable seedlings resulted.

In the culture of barley embryos in vitro James Merry of Denison University found that with embryos less than 10 days old no cell division occurred. In embryos 12 days old or older, cells continued to divide as long as the plants were grown in the culture.

Nellie A. Brown of the U. S. Horticultural Station at Beltsville, Md., reports that brushing plant tumors with colchicine results in their death.

Methods of extracting auxin from wheat are described by G. S. Avery, Jr., J. Berger and B. Shalucha of Connecticut College; and its extraction from various plant tissues by Kenneth V. Thimann, Folke Skoog and Ava C. Byer of Harvard University.

Morphology and Taxonomy.

Carl S. Wilson of Dartmouth College brings out additional evidence in favor of the telome theory of the phylogenetic origin of floral organs, in particular of the stamen. Stated in simple language, the telome theory postulates that floral organs arose directly from the modification of stem structures, and were not metamorphosed leaf structures, the latter idea having been generally accepted until recently. Studies on the morphology of the Caryophyllaceae (Pink Family), made by Betty Flanders Thomson of the University of Vermont, confirm the view that this family is related to the Primulaceae (Primrose Family).

Robert T. Clausen of the Bailey Hortorium and Cornell University has presented a taxonomic study of part of the genus Sedum, a large genus of flowering plants in the Orpine Family, Crassulaceae.

Fungi.

Ray R. Hirt and Henry Hopp of the New York State College of Forestry at Syracuse, N. Y., find that in the fungus Fomes igniarius, the sporophores (the woody brackets that grow on trunks or branches of trees) normally form one layer of tubes each year.

David L. McVickar, working at Harvard University, reports that the fungus, Pilobolus, which commonly occurs on horse dung, exhibits a diurnally rhythmic asexual reproduction. Ripening of the spore-bearing organs, which normally occurs during the morning, can be made to occur at any hour of the day or night by suitable adjustment of alternating 12 hour periods of light or darkness.

M. H. Langford and G. W. Keitt of the Wisconsin Agricultural Experiment Station at Madison, in a study of Venturia pirina, the causal agent of pear scab, find that although the fungus is hermaphroditic, it is heterothallic in the sense that the thalli are self incompatible and 'comprise at least 2 groups that are intra-group incompatible and inter-group compatible.'

Diseases.

Clayton O. Smith of the California Citrus Experiment Station at Riverside, California has artificially induced crown gall on various species of conifers, by inoculating them with Phytomonas tumefaciens.

G. H. Parris of the Hawaii Agricultural Experiment Station, reports a disease of papaya, Carica papaya, fruits induced by the fungus, Phytophthora parasitica.

At the Connecticut Agricultural Experiment Station, work is now going forward on a method of preventing, or at least retarding, the growth of the causal fungus in the Dutch elm disease. This is done by the injection of chemicals which either counteract the toxic effects of the fungus, or kill the protoplasm of the fungus without producing deleterious effects on the tree itself. For this purpose, benzoic acid, hydroquinone, and 8-hydroxyquinoline benzoate have so far given good results. However, the work is still in the preliminary stage.