Mazus delavayi

Mazus delavayi Bonati, in Bull. Herb. Boissier, sér. 2, 8: 530 (1908) (syn: Mazus divaricatus Bonati ; Mazus japonicus var. delavayi (Bonati) P.C.Tsoong ; Mazus pumilus var. delavayi (Bonati) T.L.Chin ex D.Y.Hong );

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N. Pakistan to China (W. Sichuan, Yunnan, Guangxi) and N. Myanmar: China South-Central, China Southeast, East Himalaya, Myanmar, Nepal, Pakistan, West Himalaya as per POWO;
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Kalatope id al190411 : 8 posts by 4 authors. Attachments (3)

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Mazus surculosus ? : 12 posts by 4 authors. 3 images.

Found a white Mazus on my walk today. Is it normal? To me it looks like M. surculosus only but I could be wrong. Please advise.

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The genus Mazus is no longer in the Scrophulariaceae family but Phymaceae which includes

Pl. also check comparative images & keys at ‎Mazus
Mazus japonicus (Thunb.) Kuntze is now a synonym of Mazus pumilus (Burm.f.) Steenis
This specimen appears to be quite interesting.

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I think, I should be Mazus delavayi.
Key to Mazus species in H.P.:
1. Runners present, leafy calyx shortly toothed:            M. surculosus
1. Runners absent, calyx lobed half way down:

        2. Stem hairy, calyx larger than pedicel:               M. delavayi
2. Stem glabrous or sparsely hairy, calyx shorter than pedicel:    M. pumilus

Thanks … for drawing this to my/our attention. Mostly a question of me too rapidly assuming a likely identification without checking properly – especially with plants from what are ‘low’ elevations for me. As soon as it gets to 2000m or less, my familiarity and knowledge rapidly decreases!  I know little of the Mazus genus, largely limited to a casual look at specimens growing around Manali some 30 years ago….  I now see that Stewart gave Mazus delavayii as a synonym for M.japonicus (also M.rugosus).  He found this common, ascending to 2100m in rice fields and pond borders in N.Pakistan and Kashmir.

A common mistake I have observed is for people to assume that ‘Flowers of the Himalaya’ is a FULL flora. It is merely a guide to a fraction of the total flora (often not much more than 1/10th described or illustrated), concentrating on the commonest and showiest species.  Too many users of this book automatically “match” at a quick glance what they see or photograph in the Himalaya with the single photo in that book.  Often the image does not show important characteristics which distinguish it from similar species.   This leads to numerous misidentifications.  Many do not bother to check the geographic distribution, altitudinal range or typical habit for each species to see if the identification makes sense or should be double or triple-checked!

I am not a taxonomist but would think that characteristics of calyces are stronger than the presence or not of runners. I am curious where the key to Mazus species in H.P. comes from?

I note from images taken in H.P. that some examples have much smaller calyces in relation to the flowers – though these seem also to have the calyx +/- cut to half way as well. So are these within Mazus surculosus or M. pumilus var. delavayii?

See: http://www.flowersofindia.net/Suckering%20Mazus.html  (I would not described the calyx as ‘toothed’) and https://forwildlife.wordpress.com/wild-flowers-of-kalatope-khajjiar-sanctuary/wildflowers-in-june/ (I would say the calyx here is definitely not just toothed and approaches the being lobed half way down).

As for the line drawing in FOC for M.surculosus, this shows small calyces which could be described as having toothed lobes), see: http://www.efloras.org/object_page.aspx?object_id=3540&flora_id=2 and then there are the line drawings for M.pumilus see: http://www.efloras.org/object_page.aspx?object_id=4701&flora_id=2 (I would say that the images taken by … certainly have a prominent calyx, small flowers in relation to the calyx and do not fit number 3 i.e. var. delavayii) Strange and remiss of the authors to include flowers in the line drawings of M.surculosus and not for M.pumilus which makes it difficult to judge flower/calyx size.

I remain somewhat uncertain/confused. One problem in interpreting FOI is that the authors, no matter how botanically able, may only have seen specimens from Chinese territory. The variation of species in NW may well be different/not able, so one has to be cautious here.

Anyhow, I have started to inspect Mazus more closely.  The fine photos of … (which show close-up the characteristics of the calyx) and others plus line drawings in FOC are much more useful than low resolution images of herbarium specimens. As always, “a picture paints a thousand words”.  Putting into words plant variation is often difficult.  Keys should always be viewed with caution and not accepted without question.

The currently accepted name is noted – along with various nomenclatural changes over time.  Of course not all changes/revisions are accepted.
I approach plant identification as detective work.  This is another example and further evidence that we cannot rely solely upon Hooker’s ‘Flora of British India’, which is well out-of-date (though he and other contributors did a remarkable job for the time).  Every checklist and flora (no matter how reliable they are) become out-of-date as soon as they are published!

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Four species of Mazus have been reported from Himachal Pradesh. Manali area has only two (M. surculous and M. pumilus). Other two species found in H.P. are M. delavayi (now M. pumilus var. delavayi) and M. harmandi.
The key, I have posted, was taken from “FLORA OF CHAMBA” by Singh and Sharma. Many other FLORAS have been written on plants of H.P. I have all of them with me except one on Lahul & Spiti.

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Thank you both very much for your advice. My apologies for a late reply! I wanted to revisit the plant and collect more evidence before writing. I found the plant this morning and here are some observations with photographs;

Please advise.
5 images.

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References:
POWO  Catalogue of Life Annotated checklist of Flowering plants of Nepal GBIF specimen from India