2 species recorded from New Guinea. Click on a name to go to its species page
Description (Barlow 1993)
Cyne Danser, Bull. Jard. Bot. Buitenzorg III, 10 (1929) 291, 306. - Type: C. banahaensis (Elmer) Danser (lecto, see below).
Tetradyas Danser, Bull. Jard. Bot. Buitenzorg III, 11 (1931) 361. - Type: T. perfoliata Danser.
For descriptions and synonymy see Danser, Bull. Jard. Bot. Buitenzorg III, 11 (1931) 361, under Tetradyas; Philipp. 1. Sci. 58 (1935) 33, under Cyne; Barlow, Austral. J. Bot. 22 (1974) 551, under Tetradyas. The descriptions referred to above are amended as follows: Inflorescences developing successively in the leaf axils or depressions at the stem nodes, sessile or almost so, a very contracted or capitate raceme of one or more decussate pairs of triads or rarely dyads, developing beneath the stem periderm which forms a blister-like operculum which falls in one piece or ruptures as the flowers expand; triads and individual flowers sessile or with minute peduncles and pedicels, these sometimes developing only in fruit; bracts single under each flower and together forming an involucre under each triad. Corolla 6-merous; petals separating at anthesis but coherent into a short tube at the base. Anthers basifixed, sessile.
A genus of 6 species distributed in the Philippines, the Moluccas, and New Guinea, at elevations ranging from sea level to subalpine.
Diagnostic features
The infrafarnilial classification of
Cyne and the generic group to which it belongs is outlined
above. For identification at the generic level the readily observable
morphological characters are derived from inflorescence and flower
structure.
The basic inflorescence unit (uniflorescence) in Cyne is a simple dichasium (triad) with a simple bract subtending each flower. The triads are aggregated into racemose conflorescences, but with a very contracted axis. The least specialized inflorescences are very short racemes with only one or two pairs of triads on very short peduncles, whilst the most extreme are sessile heads forming in depressions in the stem. There is no involucre of imbricate bracts which encloses the entire inflorescence, as in Lepeostegeres, and the primary diagnostic character for the genus is the operculum, developed from the stem periderm, which covers the young inflorescence. As the inflorescence expands the operculum is displaced or irregularly split.
The flowers of Cyne are hermaphrodite, 6-merous, regular and apparently similar to those of Decaisnina, being almost choripetalous and usually coherent at the base into a short tube. The epipetalous stamens have basifixed immobile introrse anthers which are sessile on the petals. The style is usually articulate just above the base.
In describing the genus, Danser (1929; 1933b) treated the capitate, sessile or subsessile inflorescence with an operculum as a single diagnostic state. The other species now included in Cyne show a clear transition to Decaisnina in inflorescence structure, although still having the unique operculum, which is probably of monophyletic origin. The diagnostic character which is assigned to Cyne in this treatment is therefore the presence of the operculum, and the genus includes species which show a series of stages in the condensation of the inflorescence to a capitulum.
Generic relationships
Cyne is apparently very closely related
to the larger genus Decaisnina (see above), which is probably
the least specialized in the group. The major difference is in
the inflorescence features described above. Although the very
contracted inflorescence develops under an operculum, species
such as C. baetorta, C. papuana, and C. monotrias
show a sequence of inflorescence reduction derived from the
expanded raceme of triads typical of Decaisnina.
Biogeographic history
For a general outline of the history
of the decaisninoid genera, see notes in the introduction and
under Decaisnina. Cyne is sympatric with Decaisnina
and, like Decaisnina, occurs on both sides of Charles's
Line. The genus presumably originated in eastern Malesia, and
was represented in the intrusive Malesian stocks which penetrated
New Guinea. Most of the species have very small areas, and appear
to be highly specialized young endemics, although their combined
distribution extending on both sides of Charles's Line indicates
a significant period of differentiation and dispersal.
la. Leaves completely sessile.. 2
1b.Leaves obscurely to distinctly petiolate.. 3
2a. Leaves of each pair united at the margins into a cup (New
Guinea) 5. C. perfoliata
2b. Leaves of each pair not united at the margins (New Guinea)
4. C. papuana
3a. Inflorescence a sessile head of usually 3 sessile pairs
of triads 4
3b. Inflorescence a contracted raceme with an axis 1-4 mm long
and usually 1 or 2 pairs of triads 5
4a. Young internodes quadrangular, leaves shortly acuminate at
the apex (Philippines) 6. C. quadriangula
4b. Young internodes terete; leaves obtuse or rounded at the
apex (Philippines) 2. C. banahaensis
5a. Inflorescence axis 3-4 mm long; triads pedunculate; lateral
flowers shortly pedicellate (Philippines) 1. C. baetorta
5b. Inflorescence axis c. 1 mm long; triads and lateral flowers
sessile (Moluccas) 3. C. monotrias
Cyne Genus Page
Updated 25 June 2003