The enigma of Sonchus oleraceous vs. S. asper

[Gurcharan Singh]

Perhaps no pair of species  has been as confusing for me as distinction between Sonchus oleraceous and S. asper. This confusion has been more so once I started observing specimens in Delhi more closely. Classical distinction between the two species is commonly based on sharply spiny leaf margins and rounded basal auricles in S. asper and absence or spiny margins are very small spiny teeth and straight basal auricles in S. oleraceous. While studying the specimens in my area critically I noticed that young specimens especially in early part of the season say in March-early April in Delhi the plants are with no obvious marginal spines and straight basal auricles with acute tips of lobes, but same plants towards the end of April have sharply spiny leaves, and some auricles are clearly rounded and some with straight acute auricles. 

      Today perhaps I found the first plant that I want to place under S. asper with confidence. It was a somewhat compact plant with ascending branches, obviously a younger plant but clearly spiny leaf margins. The auricles are much different, rounded and soft. I am uploading the  same for your comments. The plant is clearly different from plants I have seen or photographed up to now. 

--
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]

Forwarding again for for your comments in the matter please.

--

With regards,
J.M.Garg (jmg...@gmail.com)
http://en.wikipedia.org/wiki/User:Jmgarg1

'Creating awareness of Indian Flora & Fauna'
The whole world uses my Image Resource of more than a thousand species & eight thousand images of Birds, Butterflies, Plants etc. (arranged alphabetically & place-wise): http://commons.wikimedia.org/wiki/Category:J.M.Garg. You can also use them for free as per Creative Commons license attached with each image.

For identification, learning, discussion & documentation of Indian Flora, please visit/ join our Efloraofindia Google e-group: http://groups.google.co.in/group/indiantreepix (more than 1600 members & 70,000 messages on 30/5/11) or Efloraofindia website: https://sites.google.com/site/efloraofindia/ (with a species database of around 5000 species)

[J.M. Garg]

Forwarding again for for your comments in the matter please.

---------- Forwarded message ----------
From: Gurcharan Singh <sing...@gmail.com>
Date: 15 March 2011 18:25
Subject: [efloraofindia:64986] The enigma of Sonchus oleraceous vs. S. asper
To: efloraofindia <indian...@googlegroups.com>

--

With regards,
J.M.Garg (jmg...@gmail.com)
http://en.wikipedia.org/wiki/User:Jmgarg1

'Creating awareness of Indian Flora & Fauna'
The whole world uses my Image Resource of more than a thousand species & eight thousand images of Birds, Butterflies, Plants etc. (arranged alphabetically & place-wise): http://commons.wikimedia.org/wiki/Category:J.M.Garg. You can also use them for free as per Creative Commons license attached with each image.

For identification, learning, discussion & documentation of Indian Flora, please visit/ join our Efloraofindia Google e-group: http://groups.google.co.in/group/indiantreepix (more than 1700 members & 79,000 messages on 31/8/11) or Efloraofindia website: https://sites.google.com/site/efloraofindia/ (with a species database of around 5500 species).

Also author of 'A Photoguide to the Birds of Kolkata & Common Birds of India'.