Leaf Trichomes of Some Parthenium Species

Abstract

Guayule (Parthenium argentatum), a native shrub of the Chihuahuan desert, contains rubber. Guayule has been crossed with other Parthenium species in an attempt to improve its agronomic characteristics. The resulting hybrids show intermediate morphologies. Each Parthenium species has a characteristic combination of leaf trichomes. In order to recognize the contribution of each parent in future studies of hybrids, characteristics of leaf trichomes of the following Parthenium species were studied: P. tomentosum, P. fruticosum, P. Schottii and P. rollinsianum. All species studied had two or more types of trichomes, and, in some species, trichomes of upper and lower epidermal surfaces were different. The prominent trichomes on upper epidermis of P. tomentosum and P. fruticosum were simple, uniseriate, conical trichomes, which also were observed on both epidermal surfaces of P. Schottii. Extremely long, narrow, simple, whiplike, trichomes formed a dense cover on both surfaces of P. rollinsianum and on the lower surfaces of P. tomentosum and P. fruticosum. Simple, uniseriate, cylindrical trichomes, and biseriate, glandular trichomes were observed in all four species.

Morphophysiological Characterisation of Guayule (Parthenium argentatum A. Gray) in Response to Increasing NaCl Concentrations: Phytomanagement and Phytodesalinisation in Arid and Semiarid Areas

“…The leaf of guayule is generally ovate, entire and slightly acute, although its form can change according to the age, the amount of water available and position on the twig. Both the leaf adaxial and abaxial surfaces are covered with characteristic T-shaped trichomes, which give it the typical greyish-green appearance (hence, the epithet "argentatum") and aid in reducing evapotranspiration [32,42]. Although guayule is a perennial plant species, the leaves are partially deciduous, since the lower part of them shrivel up and are shed during winter drought.…”

“…As a result, even the abaxial palisade cells can receive sufficient light and contribute to the total leaf CO 2 assimilation rate. In addition, the dense covering with trichomes protects the leaf against desiccation by reducing the cuticular water loss [42]. The physiological implications of these morphoanatomical characteristics in guayule can be improved and/or enhanced with the increased leaf thickness under drought or saline conditions [32].…”

Comparative macro- and micro-morphological studies on varieties ofParthenium argentatum Gray (guayule)

“…Although its variations in leaf form, branching of the inflorescence axis, and other morphological characteristics have been studied extensively (Mehta et al, 1979;Wain et al, 1983;Healey et al, 1986), only. Mehta et al (1979) has attempted to compare a group of such morphological characters (e.g., leaf shape, trichomes) in guayule, with those found in rubber-bearing plants growing in the Mexican desert.…”

Novel trichomes increase stamen stiffness in mung bean flowers

“…1994. Des (Healy et al 1986). Also, the complement of trichomes on a plant can vary within a season as well as among species (Hardin 1979).…”