Home

Spreading the Word
Typical Appearances
Briefing
Prevention
First Aid
Medical Care
Identification
Stems
Reproduction
Foliage

The Basic            
Arrangement
Seasons
Development
Death

Variation            
Genetic
Light
Stem Growth
Soil
Male vs Female

Risk ManagementBiochemistry
Anecdotes
Bibliography

Appendices

Dermatology
Anacardiaceae

About the Author

 

Variations in Foliage

Genetics 

Poison-oak has many genes for leaf characteristics, which account for some of the leaflet variability seen, and may assist the plant in its adaptation to microclimates. For example, here are three branches collected on the same day from plants with full sun exposure growing within fifteen feet of each other at the Overlook on Upper State Park Road:

Variation

And heres an example of deep sinuses. The notches on the sides of the leaflets usually go less than half way to the central vein. This collection consists of six of the first seven consecutive terminal leaflets growing on one stem, in filtered partial sun. The sixth leaflet was curled and could not be flattened out for the picture:

 Variation

Thirty feet away the genotype was still present. Here are two of ten leaflets collected in this adjacent site. There was stronger partial sunlight:

 Variation

Heres a leaflet with no sinuses. Growing in moderate shade, it is also the longest leaflet Ive found.

 Variation

And heres the most oak like poison-oak Ive found. It resembles the leaves of the valley oak somewhat. The valley oak is on the left side of the picture:

 Variation

 

All content copyright Dr. Curt Beebe. Please do not use without permission.