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Monday - June 22, 2015
From: Nederland, TX
Region: Southwest
Topic: Plant Identification
Title: Difference between Oxalis debilis and Oxalis violacea
Answered by: Nan Hampton
QUESTION:
There are two species of pink oxalis reported to grow here in Jefferson County, Oxalis debilis (introduced) and O. violacea (native). How can I positively identify which one I have growing in my yard?ANSWER:
Oxalis violacea (Violet woodsorrel) is the native species and Oxalis debilis (Pink wood sorrel) is an escaped ornamental plant that is native to tropical America. Here is a description of O. debilis from PIER (Pacific Islands Ecosystems at Risk and here are descriptions of O. debilis var. corymbosa from Wildlife of Hawaii and from Q-Bank, a European database of invasive plants. Here is a description of O. violacea from Illinois Wildflowers and an extensive description from New England Plant Conservation Program.
Here are some comparisons of the two species using the PIER description for O. debilis and the New England Plant Conservation Program description for O. violacea.
Leaves:
O. debilis — 1.5-4.5 cm long, 2-6.5 cm wide
O. violacea — 0.6-1.3 cm long
O. debilis — oblong, 3.5-5 (-6) mm long
O. violacea — 4-7 mm long, glabrous, each with an orange gland at the apex
O. debilis — slender, flexuous, ascending, 10-25 cm long, more or less villous
O. violacea — 7-13 cm long and glabrous
Petals:
O. debilis — pinkish purple, spatulate, 11-20 mm long
O. violacea — purple to white, 1-2 cm long (10-20 mm long)
So, to summarize the most obvious differences:
- The leaves of O. debilis are longer than those of O. violacea
- The sepals of O. violacea have an orange gland at the tip; whereas, none is described for O. debiiis.
- The petioles of O. debilis are longer than those of O. violacea and they are hairy; wheras, those of O. violacea are smooth.
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