Changes

:Chromosome number: ''x''= 17, 34;''L. aromatica'': 2''n''= 34, 68,''L. indica'': 2''n''= 34, 68,''L. repens'': 2''n''= 68,''L. rugosa'': 2''n''= 34

*''Limnophila aromatica'' (Lamk) Merr., *''L. indica'' (L.) Druce.

In Malaysia, the more strongly aromatic ''Limnophila'' are considered medicinal, rather than a condiment. The smell is agreeable and resembles that of turpentine, or a mixture of cinnamon and cloves or cinnamon and citrus. In Indonesia and Peninsular Malaysia, the sap of the leaves of ''L. aromatica'' is used to clean wounds and sores on the legs although it is considered rather strong. A decoction of the leaves is given in fevers but also to promote appetite, and as an expectorant to clear mucus from the bronchial tubes. In India and Thailand, the plant is used as a cooling agent in fevers, and given to nursing mothers as a galactagogue. In Vietnam, the whole plant is used for its diuretic and anti-spasmodic action, against gravel in the kidneys, as a disinfectant for wounds and for haematuria; also for cough, snakebite and skin diseases. In China, the plant is used for the treatment of intoxication, body pains and for menstrual problems. In Malaysia and Indonesia, ''L. erecta'' has the same medicinal uses as ''L. aromatica'' . In the Philippines, an infusion of the leaves of ''L. indica'' is used for dysentery and dyspepsia. In India, the plant is considered antiseptic, and the juice is rubbed on the body for strong fevers. A liniment is made from the plant with coconut oil and used in elephantiasis. Internally, the juice is given in dysentery, combined with cumin ( ''Cuminum cyminum'' L.) and other aromatic plants. In Indonesia, a decoction of ''L. rugosa'' is used externally to cure itching eyes, and internally for mild gonorrhoea and impotence.

In Indo-China, Thailand and Indonesia, ''L. aromatica'' , ''L. erecta'' , ''L. indica'' and ''L. rugosa'' are also eaten as a condiment or sidedish, raw, steamed or cooked. ''L. aromatica'' is thought to calm the stomach after eating durian ( ''Durio zibethinus'' Murray). ''L. aromatica'' can also be grown as an ornamental, because of its attractive flowers.

''L. aromatica'' contains 0.13% essential oil, the terpenesδ-limonene andδ-perillaldehyde being important constituents. The bactericidal activities of this essential oil against ''Bacillus subtilis'' , ''Escherichia coli'' , ''Pseudomonas aeruginosa'' and ''Staphylococcus aureus'' were similar to those of a streptomycin and chloramphenicol reference. The activities of the essential oil against ''Aspergillus niger'' , ''Candida albicans'' and ''Rhizopus oryzae'' , however, were more marked than those of griseofulvin as reference. Phytochemical analysis also showed the presence of 2 flavonoids, nevadensin (= 5,7-dihydroxy-6,8,4'-trimethoxyflavone) and salvigenin (= 5-hydroxy-6,7,4'-trimethoxy flavone) as well as 2 phenolics, caffeic acid and chlorogenic acid. The related (methylenedioxy type) flavonoid 5-hydroxy-6,8-dimethoxy-3',4'-methylenedioxyflavone has also been isolated from ''L. indica'' .

 The essential oil of ''L. repens'' (Benth.) Benth. (synonym ''L. conferta'' Benth.), an aquatic herb also occurring in South-East Asia, containsα-phellandrene (52.2%) and thymol (38.2%). The antifungal activity of a 1:50 dilution in ethylene glycol was found to be of the same order of magnitude as that of griseofulvin (100μg100 μg/0.1 ml) for ''Aspergillus niger'' , ''Candida albicans'' and ''Rhizopus nigricans'' (synonym ''R. stolonifer'' ). Against dermatophytes ( ''Trichophyton mentagrophytes'' and ''Microsporum gypseum'' ), the oil at a concentration of 100μg100 μg/ml inhibited growth whereas miconazole was effective at a concentration of 10μg10 μg/ml. The oil also possessed good anthelmintic activity against ''Taenia'' sp. and ''Ascaris galli'' . The crude alcoholic extract showed significant reduction in the epithelization period compared with that of controls in excision wound models. Nevadensin isolated from the plant showed good anti-inflammatory activity in an acute inflammation model and exhibited moderate cytotoxic activity and anti-tubercular activity.

*Annual or perennial, aquatic or semi-aquatic herbs, often aromatic when bruised, glabrous or hairy; stems erect or prostrate and rooting at the nodes, simple or branched. *Submerged leaves verticillate, pinnatifid, glabrous; aerial leaves opposite to verticillate, entire to serrate, laciniate or pinnately divided, punctate; petiolate or not. *Inflorescence a lax or compact, terminal or axillary spike or raceme, or flowers solitary and axillary; bracteoles 0 or 2. *Flowers bisexual, slightly zygomorphic, 5-merous; calyx tubular, deeply 5-lobed, lobes subequal, tube with 0–-5 or 10 prominent veins; corolla tubular or infundibuliform, 5-lobed, bilabiate, adaxial lip outside in bud, entire or 2-lobed, abaxial lip 3-lobed, erect or spreading; stamens 4, included, didynamous, filaments filiform, anthers free, loculi stipitate; ovary superior, glabrous, style filiform, deflexed at apex, stigma bilamellate. *Fruit an ellipsoid to globose capsule, septically 4-valved, valves bifid, with numerous seeds. *Seed prismatic, small, 0.2-–0.3 mm long, both ends truncate.

''Limnophila'' can be found flowering and fruiting throughout the year. The production of fruits by cleistogamy on submerged stems was found in several ''Limnophila'' species, including ''L. sessiliflora'' , but has not been observed in ''L. indica'' . Hybridization is recorded from tetraploid ''L. indica'' and ''L. sessiliflora'' , both common aquarium plants.

''Limnophila'' belongs to the tribe ''Gratioleae'' and subtribe ''Stemodiinae'' , and is closely related to ''Stemodia'' and ''Morgania'' . ''Limnophila'' is divided into 4 sections: sect. ''Limnophila'' (e.g. ''L. indica'' ) has finely divided submerged leaves, and aerial leaves with parallel veins, section ''Connatae'' has similar aerial leaves, but lacks submerged leaves, section ''Integrifolieae'' (e.g. ''L. rugosa'' ) has pinnately veined leaves and a calyx without striations, while section ''Striatae'' (e.g. ''L. aromatica'' , ''L. erecta'' ) has similar leaves as the latter but a striate calyx. Most ''Limnophila'' species show a large variation in form of the leaves, hairiness and habit.

*G.H. Schmelzer