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Ensete

An annotated list of the species of Ensete.

by Gerda Rossel and David Constantine

Introduction
Species
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last updated 26/10/2007

The genus Ensete.

The genus Ensete was first described by Paul (Paulo or Paulus) Fedorowitsch Horaninow (or Horaninov) (1796 - 1865) in his Prodromus Monographiae Scitaminarum of 1862 in which he created a single species, Ensete edule. However, the genus did not receive general recognition until 1947 when it was revived by E. E. Cheesman in the first of a series of papers in the Kew Bulletin on the classification of the bananas.

Taxonomically, the genus Ensete has been getting smaller and smaller since Cheesman revived the genus with 25 species. Cheesman acknowledged that field study might reveal synonymy and the most recent review of the genus by Simmonds (1960) listed just 6. Recently the number has increased to 7 as the Flora of China has re-instated Ensete wilsonii. The species currently recognised are as follows:

E. gilletii
E. glaucum
E. homblei
E. perrieri
E. superbum
E. ventricosum
E. wilsonii

The composition of the genus Ensete is not settled definitively. For example, Simmonds (1960) comments that he can see no consistent differences between E. ventricosum and E. glaucum and that it might ultimately prove necessary to reduce the former to the latter. Simmonds also treats E. wilsonii as E. glaucum. Lock 1993 comments that E. gilletii may be no more than a subspecies of Ensete ventricosum although Akoègninou et al (2006) treat it as E. livingstonianum.

Cheesman (1947) and Simmonds (1960) mention one or two undescribed Ensete species in Thailand which have still not been described but one is now in cultivation. Musa martinii Noter from Vietnam might possibly be an Ensete. The Flora of China mentions in passing that there are 10 species of Ensete. It will be some time before anything like a complete picture emerges of Ensete or indeed the Musaceae in south-east Asia.

Characteristics of Ensete.

The genus has the following characteristics (Moore 1957, Simmonds 1960: 208 - 211; Champion 1967: 9):

Habit Large monocarpic herb.

Leaves Large, oblong, gradual transition of the upper leaves into bracts.

Petioles Variable in length, the lower ones sometimes shortest, giving the plant a rosette-like appearance; when they are longer the plant has a more Musa-like appearance.

Leaf sheaths Lax, loosely clasping the pseudostem.

Pseudostem Formed by the leaf sheaths, somewhat swollen at the base, especially in E. homblei and E. gilletii, but less so in E. ventricosum and E. glaucum.

Bracts Persistent, covering 2 rows of flowers.

Bract insertion Flowers and bracts are integrated at the base and with the floral axis; they have no abscission layer (contrary to Musa) and the flowers and bracts persist on the axis although they may shrivel as the inflorescence matures.

Inflorescence
Drooping at maturity; gradual transition in flower type from basal hermaphrodite (sometimes female) to distal male flowers. Perfect stamens have been sometimes seen in basal flowers of E. ventricosum, E. homblei and E. glaucum.

Flowers Outer perianth (compound tepal) and inner perianth (free tepal).

Outer perianth 3 linear lobes which are coherent at the two adjacent margins but are not fused or fused at the base only; two small accessory lobes may or may not be attached at the middle of the edges of the central lobe.

Inner perianth A three-lobed structure, about as broad as long (sometimes replaced by three separate lobes in E. ventricosum), with a narrow central segment which is acute or long-apiculate at the tip and which contains the midvein of the tepal; two suborbicular ragged-dentate lateral lobes enfolding the filaments.

Fruits Leathery and dry with big seeds and scanty, whitish or orange-coloured pulp.

Seed Blackish, spherical, with irregular and depressed hilum, T-shaped embryo, mean diameter; E. glaucum 9 - 12 mm., E. superbum 8 - 12 mm., E. ventricosum 12 - 18 mm., E. gilletii 7 - 9 mm., E. homblei 6-7 mm.

Pollen Granulose-papillose, with a thin exine.

Differences between Ensete species.

Ensete species can be divided into two geographic groups, African and Asian. The three African species (E. gilletii, E. homblei and E. ventricosum) differ mainly in the size of the plants and the seeds, as well as in the orientation of the leaves. The two properly known Asian species (E. superbum and E. glaucum) differ in the circumference of the lower pseudostem and the colour of the bracts (Simmonds 1960: 212; Baker & Simmonds 1953: 407-408, 414). [The Madagascan E. perrieri is too little known to be included in this discussion].

Simmonds has drawn attention to similarities between Asian E. glaucum and African E. ventricosum for instance in waxiness, structure of the bracts and flowers, colour of the sap and in seed characters. The only constant difference between the two seems to be the pigmentation of the male flowers, which are all-white in E. glaucum, while those of E. ventricosum have an orange-yellow tipped perianth, violet or purple anthers and yellow or greyish pollen. Both have wide geographic ranges but E. glaucum reportedly varies little whereas E. ventricosum is highly variable.

Differences from Musa.

The differences Cheesman highlighted to separate Ensete from Musa can be summarised as follows:

Ensete

Musa

Single stemmed monocarpic herbs with pseudostems dilated at the base. Stooling perennial herbs with cylindrical pseudostems.

Fruit with a small number of large seeds (usually > 10mm) irregularly globose and smooth. Fruit with a large number of small seeds (usually < 6mm) often irregularly and sharply angular, rarely globose and smooth and, if so, then much smaller than Ensete and easily distinguished.

Mainly African in distribution but overlaps with Musa in Asia. No native African species with an exclusively Asian distribution

Found sometimes in grassy and rocky places at altitudes where the climate is cool The commonest habitat is rain-forest country.

Haploid chromosome number 9 Haploid chromosome number 10 or more.
(This is no longer true; there are Musa sp. with haploid chromosome numbers of 7 and 9.)

Horticultural differences.

In northern climes it is very unusual to see a flowering Ensete and the most useful distinguishing characteristic horticulturally is that Ensete do not normally produce suckers whereas all Musa do. But it is by no means impossible for Ensete to produce suckers.

There are reports of Ensete suckering in the wild. Ensete homblei possibly suckers spontaneously although there is some question whether naturally suckering plants may simply be colonies of seedlings. There are clones of E. ventricosum in Ethiopia that do sucker spontaneously and this has also been noted in E. glaucum in Vietnam. Ensete ventricosum will readily produce suckers if the growing point is damaged artificially. This has been practised in Ethiopia for hundreds of years as a means of propagating desirable clones and has recently been "re-discovered" by nurserymen.

"Sucker" is not a very precise horticultural term and is defined as "a shoot arising from a plant's roots or underground stem" (Griffiths 1994). The definition does not prescribe the origin of the sucker shoot. Thus while the term sucker can be applied to both Ensete and Musa there seems to be a fundamental difference between Musa and Ensete suckers. In Musa, suckers arise from pre-existing lateral buds whereas, in my experience, Ensete suckers seem only to develop adventitiously in response to wounding. Thus in E. ventricosum, removal of the growing point does not release previously inhibited lateral buds but results in the development of a callus mass from which shoots spontaneously regenerate. The mechanisms by which suckers arise in Musa and Ensete seem quite distinct. Musella seems to be somewhat intermediate in the sense that suckers usually develop from lateral buds but can also arise adventitiously from wound tissue at the base of detached suckers.

A much less certain method of separating Ensete from Musa is the length of the petiole. Ensete tend to have short, indistinct petioles whereas in Musa petioles tend to be long and obvious. However, like leaf shape and colouration, petiole length is heavily influenced by light intensity. Ensete grown under low intensity light have abnormally long petioles, narrow leaves and poor colouration. This can cause some confusion for example when looking at plants in glasshouses at botanical gardens.

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Species

Ensete agharkarii (A. K. Chakravorti) D. K. Hore, B. D. Sharma & G. Pandey, Journal of economic and taxonomic Botany 16 (2): 447-455 (1992).
Ensete arnoldianum (E. A. J. De Wildeman, Bull. Soc. Etud. Colon. Brux. 8: 339 (1901)) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947).
Ensete bagshawei (A. B. Rendle and S. Greves, Journal of Botany, British and Foreign. 48: 169 [t. 506] (1910)) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947).
Ensete berryi R. K. Jain, Nature 187, 342 - 343 (1960).
Ensete buchanani (J. G. Baker, Annals of Botany 7: 207 (1893)) E. E. Cheesman, Kew Bulletin 2 (2): 102 (1947).
Ensete calospermum (F. J. H. von Mueller, Proceedings of the Linnean Society of New South Wales 10: 355 (1885) and in Gardeners' Chronicle series 3, 20: 369 & 467 fig. 85 (1896)) E. E. Cheesman, Kew Bulletin 2 (2): 102 (1947).
Ensete davyae (O. Stapf, Kew Bulletin 3: 102 (1913)) E. E. Cheesman, Kew Bulletin 2 (2): 104 (1947).
Ensete edule P. F. Horaninow, Prodromus Monographiae Scitaminarum : 41 (1862).
Ensete elephantorum (K. M. Schumann & O. Warburgex K. M. Schumann in A. Engler et al (eds.) Das Pflanzenreich. Engelmann, Leipzig, 1900 - . 4, 45 : 14 (1912)) E. E. Cheesman, Kew Bulletin 2 (2): 102 (1947).
Ensete fecundum (O. Stapf, Journal of the Linnean Society (Bot.) 37: 526 (1906)) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947).
Ensete giganteum (C. E. O. Kuntze, Revisio Genera Plantarum 2: 691 (1891)) T. Nakai, Bulletin of the Tokyo Science Museum 22: 12 (1948).
Ensete gilletii (E. A. J. De Wildeman, Revue des Cultures Coloniales (Paris) 8, 71: 102 (1901), and Not. Pl. Ut. Inter. Fl. Congo 1: 73 seq. and t. 5 & 6 (1903)) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947).
Ensete glaucum (W. Roxburgh, Hort. Beng. 19 (1814) (nomen), Corom. Pl. t. 300, 96-98 (1819-1820), Flora Indica 2: 490 (1824) (descr.); ibid ed. 2, 1: 669 (1832)) E. E. Cheesman, Kew Bulletin 2 (2): 101 (1947).
Ensete holstii (K. M. Schumann, in A. Engler, Botanische Jahrbuecher. 34: 121-124 (1904)) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947).
Ensete homblei (J. Bequaert ex E. A. J. De Wildeman, Ann. Mus. Colon. Marseille ser. 2, 10: 332 (1912) and Les Bananiers : 51 (1913)) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947) and R. E. D. Baker & N. W. Simmonds, Kew Bulletin 8 (3): 405 (1953).
Ensete lasiocarpum (A. R. Franchet, in Morot, Journ. de Bot. 3: 329 (1889) and J. G. Baker, Ann. Bot. 7: 208 (1893)) E. E. Cheesman, Kew Bulletin 2 (2): 102 (1947).
Ensete laurentii (E. A. J. De Wildeman, Mission E. Laurent, 1: 371-374, t. 130, fig. 61 - 62. (1907) and Pl. Trop. de Grande Culture, 1: 379 (1908)) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947).
Ensete livingstonianum (J. Kirk, Journal of the Linnean Society 9: 128 (1867)) E. E. Cheesman, Kew Bulletin 2 (2): 101 (1947).
Ensete nepalensis (N. Wallich in W. Roxburgh, Flora Indica 2: 490 (1824) and ibid. ed. 2 vol. 1: 669 (1832)) E. E. Cheesman, err. cal. N. W. Simmonds, Kew Bulletin 14 (2): 212 (1960).
Ensete oregonense S. R. Manchester & W. J. Kress, American Journal of Botany, Vol. 80, No. 11 : 1264-1272 (1993).
Ensete perrieri (P. Claverie, Comptes Rendus de l'Academie des Sciences de Paris 140: 1612 (1905)) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947).
Ensete proboscideum (D. Oliver, in Hooker's Icones Plantarum 18, t. 1777 (1888)) E. E. Cheesman, Kew Bulletin 2 (2): 102 (1947).
Ensete religiosum (J. Dybowski, Rev. Hort. 72: 262 (1900) and E. A. J. De Wildeman, Ann. Mus. Col. Marseille ser. 2, 10: 352 (1912)) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947).
Ensete ruandense (E. A. J. De Wildeman, Bull. Jard. Bot. Bruxelles 8: 111 (1923)) E. E. Cheesman, Kew Bulletin 2 (2): 104 (1947).
Ensete rubronervatum (E. A. J. De Wildeman, Bull. Jard. Bot. Bruxelles 8: 112 (1923)) E. E. Cheesman, Kew Bulletin 2 (2): 104 (1947).
Ensete schweinfurthii (K. M. Schumann & O. Warburg ex K. M. Schumann in A. Engler et al (eds.) Das Pflanzenreich. Engelmann, Leipzig, 1900 - . 4, 45 : 14 (1912)) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947).
Ensete sp. Thailand
Ensete superbum (W. Roxburgh, in Hortus Bengalensis 19: 19 (nomen) (1814), and Flora Indica 2: 2 (description) (1824), and Flora Indica ed. 2, 1: 667 (1832)) E. E. Cheesman, Kew Bulletin 2 (2): 100 (1947).
Ensete ulugurense (O. Warburg & O. Moritzex O. Warburg, Tropenflanzer 8: 102 (1901)) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947).
Ensete ventricosum (F. M. J. Welwitsch, Apont. no. 45: 545 & 587, (1859)) E. E. Cheesman, Kew Bulletin 2 (2): 101 (1947) and R. E. D. Baker & N. W. Simmonds, Kew Bulletin 8 (3): 405 (1953) with correction in Kew Bulletin 8 (4): 574 (1953).
Ensete ventricosum cultivars
Ensete wilsonii (W. J. Tutcher, Gardeners' Chronicle series 3, 32: 450 [fig. 151: 451] (1902), & Revue Horticole 34 (1903).) E. E. Cheesman, Kew Bulletin 2 (2): 103 (1947).

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Habit	Large monocarpic herb.
Leaves	Large, oblong, gradual transition of the upper leaves into bracts.
Petioles	Variable in length, the lower ones sometimes shortest, giving the plant a rosette-like appearance; when they are longer the plant has a more Musa-like appearance.
Leaf sheaths	Lax, loosely clasping the pseudostem.
Pseudostem	Formed by the leaf sheaths, somewhat swollen at the base, especially in E. homblei and E. gilletii, but less so in E. ventricosum and E. glaucum.
Bracts	Persistent, covering 2 rows of flowers.
Bract insertion	Flowers and bracts are integrated at the base and with the floral axis; they have no abscission layer (contrary to Musa) and the flowers and bracts persist on the axis although they may shrivel as the inflorescence matures.
Inflorescence	Drooping at maturity; gradual transition in flower type from basal hermaphrodite (sometimes female) to distal male flowers. Perfect stamens have been sometimes seen in basal flowers of E. ventricosum, E. homblei and E. glaucum.
Flowers	Outer perianth (compound tepal) and inner perianth (free tepal).
Outer perianth	3 linear lobes which are coherent at the two adjacent margins but are not fused or fused at the base only; two small accessory lobes may or may not be attached at the middle of the edges of the central lobe.
Inner perianth	A three-lobed structure, about as broad as long (sometimes replaced by three separate lobes in E. ventricosum), with a narrow central segment which is acute or long-apiculate at the tip and which contains the midvein of the tepal; two suborbicular ragged-dentate lateral lobes enfolding the filaments.
Fruits	Leathery and dry with big seeds and scanty, whitish or orange-coloured pulp.
Seed	Blackish, spherical, with irregular and depressed hilum, T-shaped embryo, mean diameter; E. glaucum 9 - 12 mm., E. superbum 8 - 12 mm., E. ventricosum 12 - 18 mm., E. gilletii 7 - 9 mm., E. homblei 6-7 mm.
Pollen	Granulose-papillose, with a thin exine.

Ensete	Musa
Single stemmed monocarpic herbs with pseudostems dilated at the base.	Stooling perennial herbs with cylindrical pseudostems.
Fruit with a small number of large seeds (usually > 10mm) irregularly globose and smooth.	Fruit with a large number of small seeds (usually < 6mm) often irregularly and sharply angular, rarely globose and smooth and, if so, then much smaller than Ensete and easily distinguished.
Mainly African in distribution but overlaps with Musa in Asia.	No native African species with an exclusively Asian distribution
Found sometimes in grassy and rocky places at altitudes where the climate is cool	The commonest habitat is rain-forest country.
Haploid chromosome number 9	Haploid chromosome number 10 or more. (This is no longer true; there are Musa sp. with haploid chromosome numbers of 7 and 9.)