Changes

:Chromosome number: ''x''= 16;''P. cablin'': 2''n''= 32, 34, 64;''P. heyneanus'': 2''n''= 32, 64.

* ''[[Pogostemon cablin]]'' (Blanco) Benth., in: A. DC., Prodr. 12: 156 (1848), synonyms: ''Pogostemon patchouly'' Pellet. (1845), ''P. comosus'' Miquel (1859), ''P. javanicus'' Backer ex Adelb. (1954).

* ''[[Pogostemon heyneanus]]'' Benth., in: Wallich, Pl. asiat. rar. 1: 31 (1830), synonyms: ''Origanum indicum'' Roth (1821), ''Pogostemon patchouli'' sensu Hook.f. (1885), non Pellet. (1845).

* * ''P. cablin'' : *Patchouli (En). *Patchouli (Fr)

* ''P. heyneanus'' : *Indian patchouli, Java patchouli (En)

Essential oils extracted from several other plants are sold as patchouli oil, e.g. Chinese patchouli ( ''Microtoena insuavis'' (Hance) Prain ex Briquet (synonyms: ''Plectranthus patchouli'' C.B. Clarke ex Hook.f., ''Microtoena cymosa'' Prain). ''P. cablin'' leaves for export used to be frequently mixed with leaves of ''P. heyneanus'' , ''Microtoena insuavis'' , ''Ocimum basilicum'' L. or ''Urena lobata'' L. There are synthetic patchouli substitutes, but these are expensive and do not have the broad odour profile of the true essential oil. Sometimes, solvents that have a high boiling point, such as benzyl benzoate and propylene glycol are added as extenders to adulterate patchouli oil.

*Usually pubescent, sometimes strongly scented, herbs or small shrubs. *Leaves opposite or whorled, petiolate or sessile, often doubly crenate-serrate. *Inflorescence a verticillaster, arranged in simple or branched, axillary or terminal, often densely flowered false spikes or racemes, which again are often united into a terminal panicle; bracts and bracteoles small, densely hairy, persistent; flowers .*Flowers small; calyx campanulate-tubular, 5-veined, ending in 5 subequal teeth; corolla tubular, shortly 2-labiate, 4-lobed, 3 lobes forming upper lip, lower lip entire; stamens 4, exserted from the corolla, often in 2 pairs, divaricating, filaments usually pilose, anthers unilocular; disk subentire; ovary deeply 4-partite, glabrous; style exserted, 2-lobed at apex. *Fruit consisting of 4 smooth or granulate, glabrous nutlets, enclosed in the persistent calyx.

''P. cablin'' .* Erect or ascending aromatic herb, up to 1 m tall. Stem branched, solid, angular, tomentose.*Leaves decussately opposite, thin- or thick-membranaceous, with short appressed hairs; petiole 1-3(-8) cm long; blade ovate, 5-10(-14) cm × 3.5-6.5(-10) cm, base cuneate, margin simple or double crenate-serrate, apex acute, gland-dotted below.*Spicate racemes 3-many, forming a terminal panicle 15-30(-40) cm long; verticillasters slightly apart below, closely approximate above, grey pubescent; bracts ovate to lanceolate, up to 9 mm × 4 mm, entire to toothed, imbricating.*Calyx tubular, 4-6 mm long, densely hairy outside, subglabrous inside, teeth about 2 mm long and ciliate; corolla 6-7 mm long, white, lavender-blue or violet; filaments inserted at about 2 mm in the tube, about 6 mm long, violet, soft-haired but glabrous towards the base; style 6 mm long, lobes 1.5-2 mm long.*Nutlets ellipsoidal, 0.6-1 mm × 0.5-0.6 mm, reticulate-punctate, black.  ''P. heyneanus'' . *Erect or ascending, aromatic subshrub, up to 1.5 m tall. Stem branched, slender, solid, obtusely 4-angular, subglabrous and rooting at the base, short-haired in upper part. *Leaves decussately opposite, thin-membranaceous, subglabrous to rather densely soft-haired; petiole 1-6 cm long; blade ovate, 1-14 cm × 1-8 cm, base cuneate, margin simple or double crenate-serrate, apex acuminate, gland-dotted below. *Inflorescence paniculate, terminal, 6-18 cm long; verticillasters globular, 0.5-1.5 cm apart at the base, more approximate upwards; bracts ovate to lanceolate, 3-5 mm long; calyx .*Calyx tubular, 3-5 mm long, tomentose outside, subglabrous at base inside, teeth triangular, 1-1.5 mm long, ciliate; corolla 4-5 mm long, white or with pale violet upper lip, glabrous; filaments inserted at about 1.7 mm in the tube, straight, about 4 mm long, bearded around the middle but glabrous towards the base; style 5-6 mm long, lobes 0.6-0.7 mm long. *Nutlets orbicular, 0.5-0.6 mm long, reticulate-punctate, shiny black.

The taxonomy of especially the cultivated ''Pogostemon'' species such as ''P. benghalensis'' (Burm.f.) Kuntze (northern India to China), ''P. cablin'' , ''P. heyneanus'' , and ''P. plectranthoides'' Desf. (Indian subcontinent) is not well investigated. These species are often propagated vegetatively and several cultivars seldom or never flower. It is possible that most cultivars belong to one botanical species.

Two types of oil glands occur in the leaves of ''P. cablin'' : glandular trichomes on the epidermis and mesophyll glands. The glandular trichomes consist of a large (16μm × 27μm) secretory head, a stalk of several cells and a basal cell embedded in the epidermis, but different from the normal epidermis cells. This type of secretory trichome is common in ''Labiatae'' . The mesophyll glands are complex structures located in the palisade tissue or occasionally in the spongy parenchym. They consist of a large (30μm × 38μm) secretory cell located near a small vascular bundle. The secretory cell has very dense cytoplasm and a large nucleus and is surrounded by a cuticula. The essential oil produced is contained in the space between the cell wall and the cuticula. The vascular bundles associated with the secretory cells consist of xylem and phloem elements, idioblasts and bundle sheath cells. In in vitro cultures of ''P. cablin'' tissues or cells, which do not contain mesophyll glands, no cyclic sesquiterpenes, which are characteristic of patchouli oil, are produced.

''P. cablin'' is propagated vegetatively by cuttings. In Indonesia cuttings 5-10 cm long are taken from the central part of semi-mature stems. Cuttings from 9-month-old plants give the highest success rate. Alternatively, 10-12 cm long cuttings with 3 or 4 nodes and a terminal bud are used. Cuttings are planted in nursery beds and transplanted into polybags after 3-5 weeks. Rooted cuttings are planted out in the field at a spacing of about 60 cm × 60 cm. Cuttings are sometimes planted directly into the field using cuttings 15-20 cm long and planting them at an angle of 60to 60° to the soil surface at a rate of 2-3 per hill. Adequate moisture and shade are essential during the early stages. When propagation material is scarce or when selected plants are multiplied, 2.5-5 cm long, single-node cuttings can be used, provided the nodes are buried in the rooting medium. In vitro multiplication using stem meristems has been successful in India and the Philippines. In this procedure plantlets are formed directly from meristem tissue and not from callus, which reduces the risk of mutations. The procedure involves hormone treatments to induce stem formation and shoot growth; to promote root growth, the plantlets are transferred to hormone-free medium. Plants developed from these plantlets grow well and yield an essential oil of normal composition.

''Pogostemon'' is affected by several fungi attacking the roots and leaves. ''Alternaria'' and ''Cercospora'' spp. may cause extensive damage to the leaves. ''Fomes'' , ''Pythium'' and ''Sclerotium'' spp. may affect the root system; ''Fomes'' is especially serious where ''P. cablin'' is interplanted in rubber plantations.

Nematodes, particularly ''Heterodera marioni'' in Indonesia and ''Helicotylenchus dihystera'' and ''Meloidogyne incognita'' in India cause extensive damage in ''Pogostemon'' . In some cases infestation is so serious that it reduces crop life and causes replanting to be unprofitable unless a long fallow or rotation period is observed. ''Pogostemon'' is often affected by viruses. Patchouli mottle virus (PaMoV, a potyvirus), patchouli mild mosaic virus (PaMMV, a faba-group virus) and tobacco necrosis virus (TNV) have been isolated. Virus-free plants can be produced by meristem-tip culture. Increased biomass and oil yields of virus-free plants have been reported, while the quality of the oil produced was very similar to that obtained from the original material. The rate of reinfection in the field can be high; 30% in 4 months has been observed.

Few pests cause serious damage. Crickets, grasshoppers and snails have been reported to affect ''Pogostemon'' , but they can be controlled easily. Leaf-rolling caterpillars are a more serious pest, as they are difficult to control.