Day 42 - Why is the parasitic Field Dodder spreading in Thiruvanmyur beach?
In the early days, when there was just a few here and there, I initially thought this was discarded fishing net!! This last fortnight, it has really grown and blanketed the Ipomoea (The beach morning glory).
Posting the pictures on iNat revealed the identity of Dodder. While iNat said Field Dodder (Cuscuta campestris), efloraindia seemed to also indicate the Five angled Dodder.
I asked ChatGPT for the differences between the two - and it gave me this fantastic table!
| Feature | Field Dodder (Cuscuta campestris) | Five-angled Dodder (Cuscuta pentagona) |
|---|---|---|
| Stem | Finer, thread-like, usually < 0.5 mm thick; more delicate | Thicker, coarse, often > 0.5 mm; feels slightly wiry |
| Flowers | Tiny (2–3 mm), cream-white; petals (corolla lobes) spread outward; tube is short | Slightly larger (3–4 mm), white; petals stay more erect/pointed; tube longer |
| Flower arrangement | Often in loose clusters (glomerules) that look airy | Clusters more compact and dense |
| Fruit capsule | Roundish, smooth, often slightly flattened; 2–4 seeds | More distinctly angular or 5-sided capsule (“five-angled”) |
| Seed size | ~1 mm, smooth | ~1.5 mm, slightly rougher |
I looked at the pictures again, and zoomed in on the flowers.
 |
| Field Dodder |
This is a concern for sure. First of all, Field Dodder is not even native to India, and then most importantly it is a true parasite. It has attached to the Ipomoea and is sucking nutrients away. Ultimately, the lush green Ipomoea could wither and die.
The Ipomoea stabilises the sand dune and reduces erosion. So it needs to stay healthy.
I will keep a watch on the Dodder. I wonder if all the pre-monsoon showers has led to their growth, since they germinate in humid weather.
Another question mark is whether the mechanised beach cleaner is disturbing diversity and adding to the problem. (The beach cleaner is helpful in removing the litter, for sure.)
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