Variation in Cnidoscolus texanus in relation to herbivory

Area of Science:

• Botany
• Ecology
• Evolutionary Biology

Background:

• Cnidoscolus texanus, commonly known as Texas bullnettle, is a plant species found in Oklahoma.
• Understanding plant morphological variation is crucial for ecological and evolutionary studies.
• Livestock grazing is a significant environmental factor that can influence plant populations.

Purpose of the Study:

• To investigate morphological variation in Cnidoscolus texanus populations.
• To compare variation within and among populations across different grazing histories.
• To determine the impact of herbivory on plant morphology.

Main Methods:

• Studied twelve Oklahoma populations of Cnidoscolus texanus.
• Quantified stinging hair numbers on petioles and midribs.
• Assessed the depth of leaf lobing.
• Compared morphological data between populations and site classes with contrasting livestock use.

Main Results:

• Leaf lobing depth showed no significant variation within or among populations or grazing categories.
• Stinging hair numbers exhibited significant differences within and among populations.
• Petiole stinging hairs were more numerous in heavily grazed sites.

Conclusions:

• Morphological variation exists within Cnidoscolus texanus populations.
• Selective pressures from herbivory, specifically by domesticated livestock, appear to influence stinging hair density.
• This suggests population differentiation in response to grazing intensity.