Hydrocotyle sp.

Dry Plain, NSW

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Identification history

	Hydrocotyle sp.	21 Aug 2023	Tapirlord
	Hydrocotyle sibthorpioides	21 Aug 2023	AndyRoo

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User's notes

GPSed. Difficult to determine abundance i.e. whether one or more plants? Tossing up between this and H. tripartita?

8 comments

Tapirlord wrote:

21 Aug 2023

Hydrocotyle tripartita looks something like Hydrocotyle tripartita (Pennywort) i believe. Thinking Hydrocotyle sibthorpioides

Tapirlord wrote:

21 Aug 2023

@JaneR do you know these ones?

JaneR wrote:

21 Aug 2023

I don't think Hydrocotyle sibthorpioides, because: the underside of leaf is glabrous, and the attachment point for petiole to leaf does not have a ring of hairs: the latter feature being (for me) diagnostic. See photo for 4472862 and FloraVIC. But if not sibthorpioides, then what ?

Key in FloraVIC relies on leaf shape and interpretation of whether entire or divided to base. Following the key takes to a group of Hydrocotyle with leaves not divided to base, but none are glabrous both surfaces. Thinking about habitat, it doesn't look like it is in flowing water.

For me, H tripartita is closest (in being glabrous leaf surface, and its wet habitat) but leaf shape not a good fit, and certainly different from the tri-part cuneate look in your example.
I don't think I can pin this down to species with any confidence, and suggest leaving it - for th moment - as Hydrocotyle sp.

Big thanks to AndyRoo for taking the photos or both sides of leaf, and of point of attachment.

AndyRoo wrote:

21 Aug 2023

Thanks Tapirlord and particularly Jane for considered musings. Yes it was in the ephemeral drainage line through the site that drains into Back Ck. With the La Nina years we've been having there have been the odd occasions where there has been a steady very low flow. However, for this sighting it was in a relatively flat section of the drainage line where the water flow was very very low i.e. virtually still or even still. So for the time being, Hydrocotyle sp. it is - leave it with one of you to confirm.

Tapirlord wrote:

21 Aug 2023

I went through the Vicflora key and got to the following couplet.

1. Leaves palmately divided (sometimes entire leaves also present) (H.tripitata & H.rivularis)
2. Leaves entire, but sometimes deeply lobed (H.sibthorpioides)

I think the leaves entire here, over palmately divided which suggests H.sibthorpioides. This is particularly evident in the older foliage which is starting to yellow in the background of photo 3.

I do agree with Jane that in that I'm not seeing the ring of hairs around the leaf attachment, which does complicate things. However, there are at least a few examples in image 3 where the lower leaf surface is hairy. It is by no means conclusive, but for me this leans towards H.sibthorpioides.

Weighing everything up it sounds like Hydrocotyle species is a good place to leave this one. A bit of a shame as the photography is excellent.

AndyRoo wrote:

21 Aug 2023

Ok thanks Tapirlord. My initial ID was based on this LUCID factsheet https://apps.lucidcentral.org/plants_se_nsw/text/entities/hydrocotyle_sibthorpioides.htm. Like you i am now leaning towards H. sibthorpioides, given that (a) it fits the "...both surfaces more or less sparsely bristly..." description, particularly the "...less sparsely bristly" bit, and (b) that I have previously posted pics of what I am sure is H. tripartita to SHNM (Hydrocotyle tripartita (Pennywort)), although this is yet to be confirmed or denied. But as Jane and you point out the missing ring of hairs on the leaf/petiole attachment point throws a spanner in the works.

JaneR wrote:

21 Aug 2023

just a comment from my perspective: the ring of hairs was something that Dave Albrecht alerted me in 2019 to for H. sibthorpioides, that he relied on so I have relied on it too, ever since. The challenge is to know which traits are to be most relied on: and I don't have an answer for this genus.

AndyRoo wrote:

21 Aug 2023

Thanks Jane. Yes I've learnt from Marg Ning that what Dave says needs to be heeded.

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