Date of Award:

5-1972

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Botany

Committee Chair(s)

Arthur H. Holmgren

Committee

Arthur H. Holmgren

Committee

Sid Boyle

Committee

Richard Shaw

Committee

Eugene Cronin

Committee

Neil West

Abstract

An attempt was made to determine the taxonomic status of a Salsola taxon new to Utah but found quite extensively in parts of Nevada, and California. The disciplines of cytogenetics, morphology, anatomy, chemotaxonomy, and palynology were employed.

It is the consensus of some taxonomists that this new taxon, referred to as Salsola X and which has lax perianth tips, is a variant of the Salsola Salsola paulsenii Litv. or barbwire Russian thistle taxon. Accepted taxonomic authorities on the Cheopodiaceae, Aellen and Botschantzev, consider the erect, spinose perianth tips to be a morphological character used in delimiting S. paulsenii. If only evidence from the fields of anatomy and palynology were considered, then this new taxon should logically be placed in S. paulsenii because little or no character discontinuity exists among the taxa under consideration and differentiation would be impossible on the basis of these characters alone. When data obtained from the disciplines of chemotaxonomy and particularly cytogenetics and morphology were considered then character discontinuity was great enough to distinguish among the taxa. The data justify placing what has been referred to as the lax form of S. paulsenii and Salsola X in the same species but different from the species in which S. paulsenii with the spinose perianth tips were placed.

All three taxa are typically rigid-prickly to the touch and yellow green in color, However, the perianth tips of Salsola X and the lax form of S. paulsenii are flexible and linear-spatulate in contrast to the rigid, erect, spinose perianth tips of the spinose form of S. paulsenii.

The form of the perianth tip was directly related to the chromosome number. All populations of the lax form of S. paulsenii and Salsola X examined cytogenetically had a haploid chromosome number of 27; all populations of the typical S. paulsenii taxon with spinose perianth tips had a haploid chromosome number of 18.

There were some differences in the chromatographic patterns of the Salsola species which could be used as evidence in separating them. However, differences in the patterns within a taxon were almost as great as differences between taxa. As a result it would be difficult to delimit the species using only the chromatographic evidence obtained during this investigation.

It seems illogical to place the three forms in the same species when the morphological and cytological differences are so distinct. Similarities in the data and absence of character discontinuity between the lax perianth form of S. paulsenii and Salsola X led to the conclusion that these two forms should be placed in the same species.

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