වල්පිච්ච/ගැටපිච්ච [Walpichcha/Getapichcha]Downy jasmine (Jasminum multiflorum)

An introduced scrambling or weakly climbing shrub native to India. Widely cultivated in home gardens.

Ophiorrhiza pectinata

An indigenous erect herb occurs in lowland rain forests. 

Shrubby false buttonweed (Spermacoce verticillata)

Native perennial herb of  Tropical America. Introduced and naturalized along roadsides, waste lands,etc. Rather common weed.  

දේවකගේ තැලි කටුස්සා [Devakage Theli Katussaa]/Devaka's Fan-throated Lizard (Sitana devakai)

Fan throated Lizard inhabiting dry coastal areas of  the North, Northwestern and Southeastern part of the country was formerly considered as a single species Sitana ponticeriana which is also recorded from the India. However with the recent taxonomic changes now it is considered that Sri Lanka is home to two distinct endemic species, one occurs in the Southeastern coastal areas (Sitana bahiri) and other in the Northern and Northwestern part of the island (Sitana devakai).

Devaka's Fan-throated Lizard is an endemic lizard confine to the dry coastal areas of the north and north western part of the island. However sometime it is recorded even 10-60 km from the nearest beach. It is active during the day time. Territorial behaviors of Sitana devakai are similar to its Southeastern congener Sitana bahiri.  

References:
Amarasinghe, A.A.T., Ineich I., Karunarathna D.M.S.S., Madhava W., Botejue S. & Campbell P.D., 2015 Two new species of the genus Sitana Cuvier, 1829 (Reptilia: Agamidae) from Sri Lanka, including a taxonomic revision of the Indian Sitana species, Zootaxa 3915(1): 67-98

කෙතල/කෙටල[Kethala/Ketala] (Lagenandra praetermissa)

An endemic large herb locally common along streams, rivers and rivulets from lowlands to mid hills.  

Acrostichum aureum

Probably the only fern species found in the mangroves of Sri Lanka*. It occurs usually on landward side of the mangroves and brackish water marshes. Young reddish leaves edible and made into a curry. Dried leaves are also used as thatching of temporary huts.

* Locality unknown single specimen of Acrostichum speciosum is also mentioned in the Revised Handbook to the Flora of Ceylon Vol XV Part B page 367.

කරවිල/බටු කරවිල[Karawila/Batu karawila](Momordica charantia)

An indigenous climbing herb occurs in lowland rain forests, riverine forests and cultivated areas up to 1200 m a.s.l. Fruit use in curries and pickles. Several cultivated varieties are used as vegetables.

Areca triandra

Native palm of Bangladesh, Andaman islands and Malay peninsula. Cultivated as an ornamental in gardens. 

ඉත්ත[Itha](Schefflera heterobotrya)

An endemic shrub or tree occurs in up country forests from 610 to 1900 m elevations. Sometimes found near streams. Flowering and fruiting occurs after the monsoon with full fruiting from October.

රත් කෑලිය/කොස්බඩ[Rat-keliya/Kosbada](Litsea ligustrina [Syn: Litsea longifolia/Litsea quinqueflora])

Common native tree occurs in the wet zone forest understory up to about 2000 m altitude. Bark use in medicine.

නස් නාරන්[Nus naran] (Citrus x madurensis)

Shrub or small tree cultivated in home gardens for its edible fruit. It is probably a stable hybrid between Kumquat (Fortunella spp.) and sour Mandarin species (Citrus reticulata var. austera) 

Restricted Demon (Notocrypta curvifascia)

Rare butterfly found in wet and intermediate zone jungles. Its larva feeds on Zingiber zerumbet, Zingiber officinale, Meistera trichostachya, Hellenia speciosa, and Meistera fulviceps.

වැරණිය[Veraniya](Hedyotis fruticosa)

An indigenous small shrub grows on open secondary vegetation and rocky areas on mountain tops up to about 1000 m elevations

Woodland false buttonweed (Spermacoce remota [Syn: Spermacoce assurgens])

Introduced annual herb native to tropical America. Naturalized along roadsides and waste places. 

Didymoplexis pallens

Rare terrestrial, leafless and saprophytic orchid species grows under shade of trees in carpet of fallen and decaying leaves of the wet lowland forests.

Wormbush/Pinkroot(Spigelia anthelmia)

An introduced annual herb native to tropical America. Naturalized along roadsides, home gardens and waste places in Southern and western part of the Country.

බැවිල[Bavila]/Heart Leaf Fan Petals(Sida cordata)

Common indigenous prostrate or ascending slender herb grows in grasslands, waste areas and roadsides, mainly in the dry lowlands. Whole plant used in Ayurveda medicine.

Thyas coronata

Location - Sri Jayawardenapura, Kotte.
Host Plant - Flowers (Only first instar larvae) and tender leaves (Larvae of all instars) of Rangoon creeper/Drunken sailor(Quisqualis indica) - (Sujeeva Gunasena, ‎ Personal communication, October 31, 2015)
External Links - http://www.inaturalist.org/observations/1890501

කටු තම්පලා[Katu tampala]/Spiny amaranth/Prickly amaranth (Amaranthus spinosus)

Very common introduced weed occurs along roadsides, waste and disturbed grounds and in gardens. Flowering throughout the year. The young leaves are eaten as a kind of spinach and whole plant especially leaves and roots are medicinal.

මිදි ගස්/මහ මිදි/හීන් මිදි/වල්-වෙල්-මිදි [Midi Gas/Maha Midi/Heen Mii/Wal-Wel-Midi]/Headache Tree(Premna serratifolia [Syn: Premna obtusifolia/Premna divaricata])

An indigenous shrub or tree common in coastal areas and mangroves. Flowering from December to March and August to September. Fruits black when ripe. Leaves and roots used in medicine and wood in constructions  industry.

ගස් දුම්මැල්ල/කයිල/වැල් කයිල [Gas dummella/Kaila/Wel Kayila] (Phyllanthus reticulatus)

Common indigenous shrub or small tree occurs in secondary vegetation from sea level to 1000 m altitude. Bark, roots, stem, leaves and fruits are used in medicine.

ගොඩ කිරිල්ල[Goda Kirilla]/Indian Elm (Holoptelea integrifolia)

Native tree occurs in dry lowland forests. Flowering from March to April and fruiting from April to June. Wood heavy and strong. 

Asystasia intrusa

An introduced herb native to Malaysia. It occurs in lightly shaded locations, especially in the hill country, probably escaped from gardens. 

Erebus ephesperis [Nyctipao crepuscularis]

Expanse - 8-10 cm

Reference - The Lepidoptera of Ceylon - F. Moore, F.Z.S. Vol 3 Page 148.

External Links -  http://www.inaturalist.org/listed_taxa/3589369

Sonerila rhombifolia

Rather rare endemic erect herb occurs in Southwestern wet lowland forests. Sonerila rhombifolia grows sympatrically with the Sonerila silvatica.

කහ කෝන[Kaha-kona] (Senna spectabilis[Cassia spectabilis])

Native tree of the South America. Introduced and planted as an ornamental, mostly in the hill country near tea plantations. 

හීන් උඳුපියලිය[Heen-Undupiyaliya]/Creeping tick threefoil/Tick clover(Grona triflora [Syn: Desmodium triflorum])

An indigenous prostrate perennial herb very common on roadsides, open grounds, lawns,etc from lowlands to about 600 m elevations. Flowering from June to October.

Gomphandra tetrandra

Rather uncommon shrub or small tree occurs in primary and secondary wet evergreen forests from 75-1200 m a.s.l. Ripe berries are white.

මල් සේරා[Mal Sera]/Cotton Pygmy-Goose/Cotton Teal (Nettapus coramandelianus coramandelianus)

Rather uncommon breeding resident inhabiting low country tanks and large ponds covered with weeds and lotus like water plants. It is much common in the dry zone and where it lives as pairs or small to larger flocks. Wet zone records earlier only consist of migrants during the north-east monsoon period though there are recent observations of all the year round and also breeding. It feeds on vegetable stuffs, water insects and molluscs, etc.  Cotton Pygmy-Goose breeds from January to March and again in August. It build its nest in a cavity of a tree growing near tanks and lays 8-12 eggs. 

Scrambled-egg-tree (Senna surattensis [Cassia surattensis])

Native tree of the Southeast Asia. Introduced and cultivated as an ornamental. Roots and other parts medicinal. 

Actinoscirpus grossus [Schoenoplectus grossus]

Grass like native perennial weed grows in marshy places, both inland and near the coast.  Often occurs as large community. Culms used to make baskets and mats. 

කොබෝ-ලීල[Kobo-leela]/Dwarf white orchid-tree(Bauhinia acuminata )

An introduced shrub native to Southeast Asia. Cultivated as an ornamental in home gardens. Flowering most of the year.

ඇහැළ[Ehela]/Indian Laburnum/Shower of Gold (Cassia fistula)

An indigenous tree widely cultivated as an ornamental along roadsides and home gardens. Good timber tree and whole part of the tree used in traditional medicine.

White Orange Tip (Ixias marianne)

Common butterfly flies in the dry low country scrublands. Commoner in the northern part of the island especially in the Jaffna and Mannar districts though also occurs in the south and southeastern areas. Larval host plants are Capparis brevispina, Capparis grandis and Capparis sepiaria of the family Capparaceae .  

Afrohybanthus enneaspermus [Syn: Hybanthus enneaspermus]

Common indigenous herb grows among grass in open areas of the low country. Whole plant medicinal and shampoo made from the plant removes dandruff. Flowering throughout the year.

වල් ත්‍රස්තවාලු [Wal-Trasta-Walu](Hewittia malabarica [Syn: Hewittia sublobata])

Common indigenous vine occurs along roadsides, grasslands, scrub lands, forest edges, cultivation, waste lands, etc. from sea level to about 1000 m altitude in both wet and dry zones. Flowering from June to August. 

ගිනි-කැන්ද[Gini-kandha]/Bleeding-heart tree(Homalanthus populifolius)

Probably an introduced tree native to Australia & New Guinea* (Also in Malaysia and Pacific islands) though it was considered as a doubtfully native in Sri Lanka#. It occurs in both primary and secondary forests in the hill country from  1550 m to 2000 m elevations, usually in areas adjacent to tea estates.

* Illustrated field guide to the flowers of Sri Lanka J. & J. de Vlas
# Flora of Ceylon Vol 11 Dasanayaka M.D. & Clayton W.D.*

මහ ඇපල[Maha epala]/Tropical rose-mallow(Hibiscus vitifolius)

Common indigenous shrub occurs in open places, waste lands and forest edges in the dry lowlands below 150 m a.s.l. Flowering from August to September and March to April (Probably also in other months).