The root habits of desert plants

Abstract

Root habit of Jatroptia cardiopliylla of which the horizontal extensions of the rool-syslcin were shown in plate 12 52 Plate 14. Horizontal and vertical extensions of root-systems of Carnegiea gigantea, Covilka tridcntala. and Parkinsonia microphylla Plate 15. (a) The anchorinK roots and bases of sonic lateral roots of Carnegiea gigantea 6.8 in. high. {/>) Tap root and secondary roots making up the anchoring system, and the bases of some of the superficial roots of a specimen of Carnegiea 1.2 m. high from same habitat as cactus shown in (a), (c) Tap root and bases of laterals of Parkinsonia microphylla growing near Carnegiea shown in (6) and which appears in plate 14 56 Plate 16. (o) Covillea tridentata. Horizontal and vertical extensions of roots of this plant arc shown in fig. 8. (6) Covillea from flood-plain near West Wash, showing the large number of slender adventitious roots springing from upper portion of the main roots and long tap root of which only a i)art appears, (c) Fouquieria splendens from bajada where Covillea shown in (a) was growing. Horizontal extension of roots of this plant shown in fig. 8 64 Plate 17. (a) Franscria deltoidea from flood-plain near West Wash, showing part of tap root, (b) Lateral of the first order bearing filamentous roots in groups, which, at time photograph was made, were no longer functional, (c) Krameria canescens from the flood-plain near West Wash, showing essential superficial placing of roots. (d) Lycium andersonii from near West Wash 64 Plate 18. Bird's-eye view of superficial roots of Opuntia arbuscula from bajada a mile east of Santa Cruz, showing tieir fleshy character 68 Plate 19. (o) Riddellia cooperi showing the large number of slender laterals arising from crown of tap root, and the branching feature of the bases of the laterals, (b) Riddellia from red clay soil, to illustrate lack of slender roots at crown of tap root, (c) Dasylirion texanum, with root-system partly exposed, (d) Shoot and root habit of Yucca sp. (e) Root character of Yucca radiosa 72 Plate 20. Root habit of Koeberliniaspinosa. (a) Isolated plant with prominent tap root. (b) Several shoots arising from a single sucker which still keeps its connection with parent tap root, (c) Adventitious absorption roots arising from a sucker which has not formed an independent tap root, (d) Secondary formation of tap root in a group with connecting sucker root no longer living So Plate 21. (a) Peniocereus greggii showing fleshy main root and the most important laterals, (b) Condalia spathulata. (c) Root-system of Prosopis velutina partly exposed by the caving bank of the Santa Cruz. The vertical distance from the ground surface to the water is approximately 5 m. (d) Young plant of Prosopis. The squares are centimeters, (e, f, g) Cuttings of Opuntia arbuscula (Tucson), O. arbuscula (Sacaton), and O. vivipara, respectively, all grown under similar conditions and with a large water supply Plate 22. (o) Cultures of Fouquieria splendens and of garden watermelon showing differences in character and development of ...

Wood Anatomy of Gnetales in a Functional, Ecological, and Evolutionary Context

“…Certainly, Welwitschia has no competitors in terms of deep-rooted shrubs where it grows, and the number of cooccurring angiosperm species is very small (Bornman 1978). The roots of desert wash shrubs are much deeper than those of desert scrub plants (Cannon 1911), and the daily transpirational flux of desert wash plants also is much greater than that of desert shrubs (Rundel and Gibson 1996), providing relevant comparisons to the adaptation of Welwitschia. To be sure, no desert wash shrub has broad leaves like the two leaves of a Welwitschia plant, but perhaps we could consider these two leaves as equivalent to the collective leaf surface of a desert wash shrub such as Olneya A.Gray (Fabaceae).…”

Root Architecture and Plant Productivity

“…Water availability in desert environments varies greatly with soil depth and time. Work during the early part of the century established the existence of distinct architectural classes of desert root systems, with varying emphasis on deep taproots, shallow lateral roots, or generalized exploration of the soil profile (Cannon, 1911). These classes are apparently related to the growth strategies of the shoots.…”

SOME RELATIONSHIPS BETWEEN XEROPHYTISM AND THE CONTENT OF RESIN, NORDIHYDROGUAIARETIC ACID AND PROTEIN OF LARREA DIVARICATA CAV

“…Ashby found no evidence of clogging of the very numerous and mesomorphic stomata. The fairly extensive root system of the creosote bush was considered partly responsible for its resistance to drought by some early workers (5,20). This explanation is doubtful since the root system is rather similar to those of other species of angiosperms grown under semiarid conditions by DITTMER (7).…”