C.S. Purohit, R. Kumar* & V. Maina
Botanical Survey of India, Arid Zone Regional Centre, Jodhpur, Rajasthan, India
*Correspondence: Ramesh Kumar; email: firstname.lastname@example.org
Calligonum comosum L’Her. – a member of family Polygonaceae, is reported here for the first time from India on the basis of a recent collection from Indian desert (Rajasthan). A brief taxonomic description along with photo illustration is given for its easier identification.
Keywords Calligonum comosum, Polygonaceae, new record, India.
Thar desert of western India is most densely populated hot desert in the world, which spread over nearly 12% of the land, mostly located in the state of Rajasthan with forest coverage of c. 2 million km2 consists of diverse and distinctive plants. Khan et al. (2003) listed 682 plant species including 107 grasses. Amongst them 44 plant species are considered to be rare and threatened (Kumar & Purohit, 2015). Majority of the species found here are xerophytic in nature. The region harbors a less known genus Calligonum L., which is represented by only one species, C. polygonoides L. in India and c. 158 species in the world (The Plant List, 2016).
During field exploration tour to Indian desert, Rajasthan in March 2016, an interesting specimen of Calligonum were collected. Careful study of the collected specimens and scrutiny of literature reveal its identity as Calligonum comosum L’Her. – an undescribed species in Indian flora, the same is reported here for the first time and the taxonomic description and other relevant details are provided.
Calligonum comosum L’Her., Trans. Linn. Soc. London. 1:80. 1791; R.R. Stewart, Ann. Cat. Vasc. Pl. W. Pak. Kashm. 201. 1972. Calligonum polygonoides subsp. comosus (L’Hér.) Soskov, Novosti Sist. Vyssh. Rast. 12: 153. 1975. (Figure 1&2).
Large perennial, evergreen bushy shrub, up to 3 m tall stem with rigid lignified white branches; branches woody, hard, glaucous, white to greyish-white, with swollen nodes and long internodes. Leaves subulate, small, 1 – 5 mm long. Inflorescence in long clusters; pedicel as long as
or shorter than the perianth; flowers small, silvery-white, sweet smelling; perianth segments 5, 3 – 4 × 2 – 3 mm. Fruit 12 – 13 mm across. Nut fusiform, somewhat twisted, 7 – 8 × 3 mm, 4-ribbed, ribs setose, setae seriate, 3 – 5 times branched, dilated and more or less connate at the base, soft or little fragile.
Phenology: Fl. & Fr.: February – April.
Distribution: India (Rajasthan, Bikaner, Sattasar & Chattargarh –present study), Pakistan, other part of Western Asia and Africa.
Specimen examined: India: Rajasthan, Bikaner district, Sattasar, 02.03.2016, Kumar & Purohit 31773 (BSJO). Rare in the study area.
Notes: Calligonum comosum is sometimes treated as a subspecies of C. polygonoidesL., however, it is clearly distinct from the latter in having smaller leaves, white flowers, larger nuts and pedicel mostly shorter or sometimes equaling the perianth lobes (Figure 1).
Khan, T.I., Dular, A.K. and Solomon, D.M. 2003. Biodiversity Conservation in the Thar Desert; with Emphasis on Endemic and Medicinal Plants. The Environmentalist, 23: 137-144.
Kumar, S. and Purohit, C.S. 2015. Conservation of threatened desert plants. Scientific Publishers, Jodhpur pp. 148.
The Plant List 2016. Version 1.1. Published on the Internet; http://www.theplantlist.org/accessed on 14-06-2016.