Commelina benghalensis L. & Commelina benghalensis var. benghalensis- two different accepted names

[J.M. Garg]

Dear all,

Pl. see the following accepted names as per 'The Plant List': http://www.theplantlist.org/tpl/search?q=Commelina+benghalensis+

 

Commelina benghalensis L.

http://www.theplantlist.org/tpl/record/kew-233742 (Gives no syn.)

Commelina benghalensis var. benghalensis :

http://www.theplantlist.org/tpl/record/kew-233743 (Gives syn. like Commelina canescens, Commelina cucullata, Commelina delicatula, Commelina mollis, Commelina nervosa, Commelina procurrens, Commelina prostrata, Commelina turbinata etc.)

 

Pl. clarify what it actually means for a layman like me.
--
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[Ritesh Choudhary]

Oh, very innocent question! ;-)

Both are same sir! This is called var. typica which is automatically
established whenever a new species is described.

Like Mangifera indica var. indica will automatically be established
with the description of M. indica.

Hope I am able to convey my message to you.

Best regards,
Ritesh.

[J.M. Garg]

Thanks, Ritesh ji,

But then why 'The Plant List' doesn't give any syn. for Commelina benghalensis L., while giving so many for Commelina benghalensis var. benghalensis. Also why both are given as accepted names & not only Commelina benghalensis L. as accepted name?

[Ritesh Choudhary]

I think they just picked up this name form some other data source.
That's why the confidence level is very low in C. benghalensis var.
benghalensis. Tropicos also follows the same pattern.

Regards,
Ritesh.

[Gurcharan Singh]

Garg ji

This appears to be one of the several slips in Kew Plant List. I have often been telling my students: "A species will either have no infraspecific taxon (subspecies, variety, forma), or it will have a minimum of two". If there is no other variety within (at least I could not find) C. benghalensis, then there is no sense in writing C. benghalensis var. benghalensis. There is no need to write even var. typica, if no other variant exists.

    It is like this. Supposing there is a type a (herbarium specimen) on the basis of an author names and describes a particular species, say Commelina benghalensis in this case, all specimens identified with this species (say a1, a2, a3, a4, etc) will get this name. Now supposing an author (same or some one else) discovers a specimen (say type b) which he thinks belongs to the same species but differs in certain characters from type a, and gives it a name say Commenlina benghalensis var. gargii, it will automatically establish the type variety (type a) which will be named as var. bengalensis (with no author citation, because it is automatically created; earlier authors used to call it var. typica).

    Perhaps we will have to find if there is any other variety ever described within C. benghalensis, to automatically establish var. benghalensis. If there is none var. benghalensis is redundant.

-- 
Dr. Gurcharan Singh
Retired  Associate Professor
SGTB Khalsa College, University of Delhi, Delhi-110007
Res: 932 Anand Kunj, Vikas Puri, New Delhi-110018.
Phone: 011-25518297  Mob: 9810359089
http://people.du.ac.in/~singhg45/ 

[Ritesh Choudhary]

Thanks for nicely clarifying the facts sir!

Regards,
Ritesh.

[Gurcharan Singh]

I dug out some more information. One variety C. benghalensis var. hirsuta (Wight) Clarke was recognised by C. B. Clarke in 1881 (based on Heterocarpus hirsutus of Wight) and subsequently named Commelina hirsuta (Wight) clarke in FBI in 1892. Later is considered as illegitimate name (as the name has been used for other species) and considered as synonym of Commelina coelestis Willd. That leaves only one type within C. benghalensis, and again no justification for var. benghalensis. 

Coincidently C. benghalensis subsp. hirsuta (Clarke) Morton has also been published, and although not listed in Kew List meets the same fate due to common basionym. 

-- 
Dr. Gurcharan Singh
Retired  Associate Professor
SGTB Khalsa College, University of Delhi, Delhi-110007
Res: 932 Anand Kunj, Vikas Puri, New Delhi-110018.
Phone: 011-25518297  Mob: 9810359089
http://people.du.ac.in/~singhg45/ 

[J.M. Garg]

Thanks a lot Singh ji & Ritesh ji.