Observations on Acalypha deamii (Euphorbiaceae) in Ohio

Castanea, Jun 2003 by Becus, Marjorie S

In growth form, A. deamii plants had horizontal leaves, not at all drooping until late in the season (October). The petioles were arranged so that all the upper leaves lie in a planar surface, parallel to the ground. This "flat-top" appearance of the plant was pronounced when beside A. rhomboidea and the other associates, and served as a diagnostic field mark. The leaves of A. deamii were more ovate, greener with no coppery color, and usually were not bug-eaten, in contrast to the A. rhomboidea. The bracts of A. deamii were not crowded like those of A. rhomboidea, until late in the season when the growth habit changes.

Acalypha encountered had approximate seed lengths of either up to 2 mm or 2.5-4 mm. No intermediates in seed size were observed. The smaller seeded plants containing three seeds were A. rhomboidea, and the larger seeded plants containing two seeds were therefore A. deamii, in agreement with Levin (1999). Sometimes there were four seeds in the bract. When four were present, they were greater than 2.1 mm in length unless they had aborted. Acalypha rhomboidea may also have six seeds instead of the usual three. When the number of seeds doubled, the bracts were usually larger.

Fernald (1950) stated that Acalypha deamii is "coarse throughout" (p. 961). Tall plants of both A. deamii and A. rhomboidea were observed growing to 60 cm., but based upon my observations, coarseness is not a character of A. deamii.

Particular care was taken to determine if drooping leaves were consistently found on plants of A. deamii. This character is mentioned in various references (Beam 1940, Fernald 1950, Gleason and Cronquist 1991). It apparently is based upon the field observations of Beam, as related by Weatherby. Weatherby's original description of this species (as A. virginica var. deamii) said "Mr. Beam states that the leaves regularly droop, as in A. ostryaefolia, and that they do not in ordinary A. virginica (A. rhomboidea following current nomenclature)" (1927, p. 198). The leaves on plants of A. deamii found in August and September were horizontal. On one occasion in early September, I witnessed drooping of the leaves when a sudden summer shower with gusty winds and a brief, but heavy downpour occurred. Before the shower, the leaves were horizontal, but afterwards, all of the A. deamii plants had drooping leaves. It became very easy to recognize and count the A. deamii plants among the Pilea pumila and Laportea candensis. The summer of 2001 was relatively wet in southern Ohio, without the usual late summer drought. This may have contributed to the robust, upright plants.

The transplanted A. deamii were in partial shade. When the sun shown on the leaves, they drooped, but when the afternoon shade reached the leaves, they responded by becoming horizontal. However later in the season when the garden became dry, the leaves drooped and did not respond to watering. The plants survived for another month and continued drooping. Plants observed in the wild were drooping by mid-October and remained that way until they senesced. Apparently, once the plants have been severely water-stressed, they survive but do not return to their horizontal position.