Thanks Sir for throwing light on Conyza in details On Mon, Oct 24, 2011 at 8:52 PM, Gurcharan Singh <[email protected]> wrote:
> *Conyza bonariensis* (L.) Cronq., Bull. Torrey Bot. Club. 70: 632. 1943 > syn: *Erigeron* *bonariensis* L; *Erigeron* *linifolius* Willd. > > It is quite common to find small flowered (rather small headed) species of > Conyza throughout India along roadsides and wastelands. They are much more > commoner in temperate climates. During my last visit to Kashmir I found that > larger headed of the two, more robust, long hairy and low growing Conyza > bonariensis (syn: Erigeron linifolius) had come in flowering and more > delicate with smaller heads, taller with branching in the upper part Conyza > canadensis came up to flowering towards end of June. This year with extended > stay in Kashmir i found that by middle of july another very tall often > growing to the height of 1-2 m, much more robust plant had come up and > started flowering, but by the time C. canadensis had almost started to > disappear. Initially I thought this to be late flowering population of > Conyza canadensis, but when It came to flowering in August I discovered that > it was very distinct from Conyza canadensis in robust habit, broader leaves, > larger heads and phyllaries with much shorter hairs. It was finally > identified as Conyza albida now correctly known as Conyza sumatrensis, a > species often confused with the other two. Here is the key to separate them > > 1a. Plants usually shorter than 50 cm; lateral branches equalling or > overtopping main axis; heads 5-8 mm across; > ray corolla shorter than 0.3 mm; fruiting head 8-10 mm across, pappus > 3-4 mm long; lower leaves > linear-lanceolate, upper > linear.............................................................................................................Conyza > bonariensis > 1b. Plants usually taller than 50 cm; lateral branches shorter than main > axis; heads less than 6 mm across; > lower leaves lanceolate or oblanceolate, upper > linear-lanceolate............................................................ > (2) > > 2a. Ray corolla shorter than 0.3 mm; heads 4-6 mm across; fruiting head 7-8 > mm across, pappus 3-4 mm > long; lower leaves oblanceolate, upper linear-lanceolate; plants > densely hairy, phyllaries short > > hairy................................................................................................................................................Conyza > sumatrensis > 2b. Ray corolla 0.3-1 mm long; heads 2-4 mm across; fruiting head 5-6 mm > across, pappus 2-3 mm long; > leaves lanceolate; plants sparsely hairy; phyllaries with few long > hairs...................................................Conyza canadensis > > > > > > -- > 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/ > > -- Regards Dr Balkar Singh Head, Deptt. of Botany and Biotechnology Arya P G College, Panipat Haryana-132103 09416262964
