Lemna aequinoctialis

Images by Surajit Koley & Prashant Awale (Id by Milind M. Sardesai) (Inserted by J.M.Garg) (For more photos & complete details, click on the links)

Following is the other species of family lemnaceae with the identification key
1. Plant root less................Wolffia
1. Plant rooting....................2
 2. Roots solitary.................Lemna
 2. Roots several.................Spirodella 

Lemna aequinoctialis
Welw. (lesser duckweed) is a tiny, floating aquatic plant found in quiet waters in tropical and subtropical regions.
Fronds are generally 3-nerved, green, up to 6 mm long. Flowers are 1-ovulate, the small utricular scale open on one side. Seeds have 8–26 ribs.[1]
(From Wikipedia on 11.10.14)  

Avachitgad pond-- 150710-PKA3 : 12 posts by 8 authors. Attachments (4)
Water Cirstern at Avachitgad fort near Roha.
Date/Time: 21st July 2008 / 12:30PM.
Azolla sp is a dichotomously branched free floating aquatic fern is naturally available mostly on moist soils, ditches marshy ponds 
it is Lemna perpusilla Torr. Fl. N. Y. 2: 245, 1843; Sharma et al, Fl. Mah. St. Monocot. 231, 1996.
Free floating small herb.
Following is the other species of family lemnaceae with the identification key
1. Plant root less................Wolffia
1. Plant rooting....................2
 2. Roots solitary.................Lemna
 2. Roots several.................Spirodella 
The following link shows the difference between wolffia and ABOVE aquatic species

The Avchitgad Pond plant is not Azolla but Lemna aequnictialis
Yah...these are Lemna commonly called Duck-weed.
In Bengali, we call it 'Panaa'.
It is very common in most ponds of India, and form such a continuous layer on the pond surface, that sometimes a pond may be mistaken for a
grassy field at dusk. 
kindly refer following book
Cook, C.D.K. (1996) Aquatic and Wetland Plants of India. Oxford University Press. The plant given is of Lemna aequinoctialis 
indeed, Entengr�tze (duck jelly). seen in germany too, especially on standing water.
more photos of Lemna paucicostata i Think ??? from my field Lohari Panipat
Attachments (3)

I think this is Lemna minor L. (the common duckweed)

Araceae Fortnight 1 Aug to 15 Aug 2014 : Lemna minor L. : SK-34 :  9 posts by 4 authors. Attachments (1).
Earlier post - efi thread
Neither this one nor the earlier upload is L. minor L., it is L. aequinoctialis Welw. (syn. Lemna paucicostata Hegelm.; vide Bengal Plants).
Experts/Seniors/scholars please go through the paper and express your views.
(i) Fronds ovate, obovate to elliptic or oblong, shiny green or sometimes reddish; 1 to 10 mm, 1.3 - 2x as long as wide; root 0.5 to 15 cm = minor
(ii) Fronds ovate-lanceolate, obovate to lanceolate, obovate to oblong, shiny bright green; 1 to 6 mm, 1-3x as long as wide, root 0.5 to 3 cm = aequinoctialis
Too close to decide without microscope! I have also noted that no distinct papilla can clearly be seen in this picture. Moreover, Lemna aequinoctialis is described as having asymmetrical fronds, which is not the case in these uploaded pictures, yet the size - smaller than 5 mm, frond colour, root length are closer to it.
Frond symmetry : it is interesting to note that L. minor photographs found in following sites has asymmetric fronds -
L. turionifera has a dorsal median line of small papillae, but fronds are obovate or nearly orbicular.
L. perpusilla has smaller apical papilla
So, I think this plant should be L. aequinoctialis. Attached here another photograph where apical papillae can be seen on fronds. Please correct me if I am wrong.
This is another floating plant, very common in ponds.
Species : Lemna minor L.
Bengali name : KHUDI-PANA
Habit & Habitat : very small common aquatic plant covering the entire water surface in ponds
Date : 19/8/12, 10.20 A.M.
Place : Hooghly
sites visited :