Effects of a Severe Freeze on Native Woody Plants in the Lower Rio Grande Valley, Texas

Abstract

The effects of a severe freeze in December, 1983 on the native plants of the lower Rio Grande Valley, Texas were determined for 75 species. Damage was initially assessed by examining leaves, apical meristems, and cambial tissues of stems. Initial assessments were confirmed by surveys in the spring when new leaves were present. Forty-three species were either undamaged or had only minor leaf damage. Twenty-two species with damaged leaves had intact apical meristems or showed evidence of damage for less than 10 cm below the apical meristem. Three species, Leucaena pulverulenta, Cordia boissieri, and Karwinskia humboldtiana, had more extensive damage, i.e., 10 cm - 40 cm below the apex, but showed evidence of recovery by the presence of undamaged cambial and phloem tissues below the apex. Eight species, Avicennia germinans, Capsicum annuum var. glabriusculum, Cereus pentagonus, Chiococca alba, Citharexylum berlandieri, Erythrina herbacea, Iresine palmeri (male plants), and Petiveria alliacea, were seriously damaged. Temperatures lower than those occurring in December, 1983, or similar temperatures for much longer periods of time, would be necessary to kill most of the native species in the lower Rio Grande Valley, Texas.