සුදු කිඹුල්වැන්න[Sudu Kimbulwenna]/Water smartweed (Persicaria pulchra [Syn: Persicaria attenuata/Polygonum tomentosum/Persicaria attenuata subsp. pulchra/Polygonum pulchrum)

Common native herb occurs along tank margins, ditches, paddy fields and such wet places in the lowlands. Particularly in the dry zone. 

Sri Lankan Cascader (Zygonyx iris ceylonicus)

An endemic dragonfly rather common at mid elevations of the southwestern wet zone. Also occurs in the intermediate zone, but absent in the coastal areas and higher hills. Fast flowing water near waterfalls and cascades are the preferred habitats of this rather large size cascader. It can be seen gliding continuously over the water with swift turns in such habitats. 

Scrotochloa urceolata [Syn: Leptaspis urceolata]

Rather uncommon indigenous perennial occurs in low country to mid hill forests.  

Garlic Vine (Mansoa hymenaea)

An introduced vine native to the central America. Cultivated in gardens. Bruised leaves has a garlic smell, hence the name Garlic vine. 

තිබ්බටු/ගෝන-බටු[Tibbatu, Gona-Batu] (Solanum torvum)

Common introduced shrub naturalized along roadsides and waste places especially in the wet zone up to about 1400m alt. Flowering throughout the year. 

Artillery Plant/Gunpowder plant (Pilea microphylla)

An introduced prostrate herb native to tropical America. Naturalized in the low country and common in the crevices of stone walls, moist walls of houses, and gardens. Also cultivated in pots. Flowers very small (0.05 - 0.15 cm) and male flowers explosively discharged their pollen into the air. Hence the above vernacular names.  Flowering and fruiting occurs throughout the year.

නිල් මොණරැස්ස[Nil Monarassa] (Utricularia reticulata)

An indigenous insectivorous* terrestrial herb occurs in marshy grasslands, shallow wet soil overlying rocks, paddy fields and pond margins in the low country up to about 750 m a.s.l. Flowering from October to March and throughout the year in permanently wet habitats.

* Read  Bladderwort (Utricularia moniliformis) for more details on small protozoans and insect larva capturing traps of bladderwort flower family plants.  

Scarlet Sage/Tropical Sage (Salvia splendens)

An introduced ornamental shrub native to the Brazil. Popular bedding plant of gardens.

වල් දෙහි/යකිනාරන්/‍යක් දෙහි[Wal dehi/Yakinaran/YakDehi] (Atalantia ceylanica)

An indigenous shrub occurs in both dry and wet low country and lower hills.  Leaves and roots are used in traditional medicine.

බලු නකුට[Balu nakuta]/Jamaican vervain/Blue snakeweed(Stachytarpheta jamaicensis)

Native herb of tropical America. Introduced and widely naturalized along roadsides, waste places, open country, etc. Flowering throughout the year. 

Persicaria chinensis

Native woody herb or sub-shrub climbing and scrambling over other vegetation along roadsides and forest margins in wet montane areas. 

Cola-nut/කෝලා [Colay] (Cola nitida)

Native plant of West tropical Africa from Guinea to Ghana. Introduced into Sri Lanka in 1879. The seeds contain caffeine and are used in the manufacture of soft drinks.

නෙළු[Nelu] (Strobilanthes vestita)

An endemic under shrub occurs in secondary hill forests from 900 to 2000 m a.s.l, usually near streams.  

කලුකම්බේරිය[Kalukamberiya] (Solanum americanum)

An introduced and naturalized common weed in cultivation, roadsides, waste places, especially in the montane zone up to 2000 m a.s.l. Flowering throughout the year. Native to sub tropical and tropical America. The leaves are sometimes used as a vegetable.

Golden dewdrop/Brazillian skyflower/Heliotrope bush/Pigeon berry(Duranta erecta[ Duranta repens])

An introduced shrub or small tree native of Florida to Brazil and the Caribbean islands. Cultivated as an ornamental in gardens. Flowering throughout the year. 

Ophiorrhiza glechomifolia

Very rare critically endangered endemic procumbent herb occurs in lowland rain forests. 

දං/හීන් දං [Dan/Heen dan] (Syzygium caryophyllatum)

 Native shrub or shrubby tree common in the secondary forests and open sandy areas of wet lowlands and margins of the intermediate zone. Fruits edible. Flowering from February to May.

Firebush/Hummingbird bush/Scarlet bush/Redhead(Hamelia patens)

Native shrub or small tree of tropical and sub tropical America. Introduced and widely cultivated in home gardens.

අග මුල නැති වැල් [Aga mula neti wel]/Golden Dodder/Field Dodder (Cuscuta campestris)

Introduced and naturalized parasitic leafless vine native to temperate and tropical North America. Common in paddy field margins, roadsides, railway tracks, waste grounds, etc. from sea level to about 1000 m a.s.l. on varies host plants (About 161 plants were observed by a study including rice*) . It is widely distributed in the dry lowlands.  Mikania cordata and Wedelia trilobata appear to be the primary host plants.

අග මුල නැති වැල්/Dodder (Cuscuta chinensis) 

Trimen H., 1895 and Austin, 1980 identified cuscuta spp. found in the low country as Cuscuta chinensis. Trimen in 1895 reported that it is very rare and only found in the suburbs of the Colombo parasitizing on grass, low herbs and shrubs. Austin in 1980 claimed that Cuscuta seeds may have been introduced to the country with imported rice from China. Base on a taxonomical study conducted on Cuscuta species found in the low country in 2004* it was revealed that most probably the above mentioned C. chinensis is an incorrect identification of Cuscuta campestris.

References:

*Jayasinghe C., Wijesundara D.S.A., Tennekoon K.U. & Marambe B. 2004, Cuscuta species in the lowlands of Sri Lanka, their host range and host - parasite association, Tropical Agricultural Research Vol. 16: 223-241 (2004)

Trimen H. 1895, Handbook to the Flora of Ceylon.

Austin D.F. 1980, Convolvulaceae. pp. 305-307, In: Dasanayaka, M.D. & Fosberg F.R.. Revised Hand Book to the Flora of Ceylon, Vol 1.

White Alder (Turnera subulata)

An introduced ornamental herb native to tropical America. Cultivated in gardens. Also escaped and naturalized along roadsides. 

කොටිකන් බැබිල/බැබිල [Bebila/Kotikan bebila]/Paddy's luceme (Sida rhombifolia)

Common indigenous erect herb occurs along river and stream banks, roadsides, waste places, paddy fields, forest clearings, etc. from sea level to to 2000 m elevations.

* Sida alnifolia L. is a synonym of Sida rhombifolia subsp. alnifolia (L.) Ugbor.

Strychnos benthamii

An endemic shrub or small tree, rarely occurs in both wet and dry lowlands. But small leave state is common in the hills.

අසමෝදගම්/Slender Celery/Marsh Parsley (Cyclospermum leptophyllum[Syn: Apium leptophyllum)

Native plant of Eurasia. Introduced and grown as a vegetable. Naturalized in open waste grounds about 1600 m elevations of Haputale. Flowering from March to April and probably also in other months.

Scarlet African Morning Glory (Stictocardia macalusoi)

An introduced ornamental liana native to the southern Somalia. Flowers open at dawn and close near sunset. Cultivated in gardens. Stictocardia beraviensis (Hawaiian Sunset Vine/Hawaiian Bell/Braveheart Vine ) is a closely related species which is extremely hard to tell apart from this.

හීන් මදු/හවරි මදු/ආපසු මදු [Hawari-Madu/Heen-Madu/Apasu Madu] (Xenostegia tridentata [Syn: Merremia tridentata])

Common indigenous vine occurs in disturbed places, roadsides, grasslands, cultivated areas and rocky lands of  both dry and wet lowlands. Commoner in the dry zone. Flowering from April to June.

Southern Duffer (Discophora lepida)

Rather rare butterfly of southwestern wet lowland rain forests with bamboo undergrowth. It flies at dawn and dusk. Larva feeds on Ochlandra stridula [Bamboo/බට] leaves.

China aster (Callistephus chinensis)

An introduced annual herb native to the China and Korea. Cultivated as an ornamental in gardens. Varies cultivars available with flowers of many colors. 

Firewheel/Indian blanket/Indian blanketflower/Indian paintbrush/Sundance (Gaillardia pulchella)

Native plant of North America. Introduced and cultivated in gardens as an ornamental. 

Bluewings/Wishbone flower (Torenia fournieri)

Native herb of Indo China. Introduced and cultivated in gardens. Flowering from March to June and September (Possibly in other months as well). Various cultivars with pink, violet and blue flowers exist.