The Genus Phalaenopsis Subgenus Polychilos
The Genus Phalaenopsis Subgenus Polychilos
David Lafarge Editor of the French Orchid Society Journal
T he subgenus Polychilos ( Breda ) Christenson is primarily centered in Indonesia and the Philippines , but has a few species distributed as far west as northeastern India ( Christenson , 2001 ). However , the monophyly of the subgenus Polychilos is not supported by DNA studies
( Tsai , 2011 ). The type species for the subgenus is Phalaenopsis cornu-cervi ( Breda ) Bl . This subgenus is characterized by its fleshy , waxy flowers bearing a pair of calli on the lip . With the exception of P . floresensis and P . micholitzii , most of the species have showy , colorful flowers . One of the remarkable traits of this subgenus is the post-pollination greening of the perianth . The petals and sepals turn green soon after fertilization , which might be a way to enhance photosynthates coming from the parent plant to the developing fruit and seeds .
Phyau Shim ( 1982 ) separated subgenus Polychilos from Phalaenopsis as a distinct genus based on Polychilos Breda , Kuhl & Hasselt ( 1827 ). This division would require further division of the genus into at least five genera . The broad approach for the genus is followed here : it seems better to keep these species within the genus Phalaenopsis . The subgenus Polychilos is divided into four sections : Polychilos , Fuscatae , Amboinenses , and Zebrinae ( Christenson , 2001 ).
Section Amboinenses
This section is the larger of the genus and is characterized by the round , star-shaped flowers and the large , overlapping segments . Phalaenopsis amboinensis J . J . Sm . ( syn . Polychilos amboinensis ( J . J . Sm .) Shim , Phalaenopsis psilantha Schltr ., Phalaenopsis hombronii
Finet ) is an Indonesian epiphyte , which bears three to four rounded , elliptic leaves reaching 24 x 10 cm . Inflorescences are arching racemes born between leaves and can branch
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on well-established plants . Each ramification is few flowered . Waxy flowers are creamy white to greenish yellow , marked with brown to red concentric , transversal markings ( Figs . 1 & 2 ). Some individuals are nicely scented . The greenish yellow form is described as P . amboinensis var . flavida by Christenson in his monograph . The albino form lacks anthocyanin pigments and is white with yellow markings ( Fig 2 ). Phalaenopsis gigantea J . J . Sm . ( syn . Polychilos gigantea ( J . J . Sm .) Shim ) is a very large epiphyte ( the largest in the genus ), originating from Sabah . The thick , leathery leaves ( 5-6 ) reach up to 70 x 25 cm , while those of the sister species , P . doweryënsis Garay & Christenson ( Fig . 3 ) measure only up to 25 x 10 cm . Inflorescences , rarely branched but on older subjects , measure about 40 cm long and appear between the leaves . The flowers can be up to 5-6 cm and are scented . The floral segments cover each other , and the flower shape is round . Flower color is cream to yellow , marked with brown to red or purple spots which form rather concentric circles ( Fig . 4 ). This species is not frequently encountered in collections due to its slow growth and to the large size of mature plants . The yellow to greenish basal color form is sometimes called P . gigantea var . aurea Christenson . Another remarkable form which does not exhibit markings of the flowers is known as P . gigantea f . decolorata ( Braem ) Christenson . This variant , illustrated by Sweet as the “ flava form ” clearly exhibits purple to brown spots near the apex of petals and sepals . These spots are only attenuated near the center of the flower . I have not had an occasion to observe this form directly , and it is hard to base an opinion only on a single photograph , but this could be an aberrant flower or a fading flower , aging or pollinated .
Phalaenopsis | First Quarter | Volume 23 | 2013
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