A reconsideration of the infrageneric classification of Homalium Jacq. (Salicaceae)
Author
Applequist, Wendy L.
Missouri Botanical Garden, P. O. Box 299, St. Louis, Missouri, 63166 - 0299, U. S. A.
wendy.applequist@mobot.org
text
Candollea
2016
2016-08-02
71
2
231
256
journal article
3101
10.15553/c2016v712a9
f620158d-04f5-457c-b6de-6dd9a311d426
2235-3658
5721656
4.
Homalium
sect.
Eumyriantheia
Warb.
in Engler & Prantl, Nat. Pflanzenfam. III(6a): 36. 1893.
÷
Myriantheia
Thouars
,
Gen. Nov.
Madagasc.: 21. 1806
.
÷
Homalium
[unranked as §]
Myriantheia
(Thouars) Baill., Bull. Mens. Soc. Linn. Paris
1: 576. 1886
[as
Myrianthea
].
÷
Homalium
sect.
Myriantheia
(Thouars) Kuntze
in Post & Kuntze, Lex. Gen. Phan., Prop.: 285. 1903
[as
Myriantheja
].
Typus
:
Homalium laxiflorum
(Tul.) Baill.
(
÷
Myriantheia laxiflora
Tul.
) (designated by
Sleumer, 1973: 315
).
Stipules
axillary, free.
Inflorescences
racemose or paniculate; bracts ovate to deltoid, sometimes broadly, of small to moderate size; bracteoles usually 2 per flower, often borne on pedicel (1 per flower, or absent or rapidly caducous).
Flowers
pedicellate with pedicels articulated (in
H. trigynum
sessile or short-pedicellate); perianth 4-5(-6)-merous.
Sepals
oblong to elliptical, ovate or obovate, sometimes narrowly (oblanceolate), very little accrescent; calyx tube funnelform, in fruit becoming convex to cup-shaped or nearly hemispherical (in
H. trigynum
short-cylindrical or turbinate becoming broadly ellipsoid in fruit); sepal glands usually large, oblong to elliptical or irregularly trapezoid (semicircular), sometimes elevated.
Petals
obovate to oblanceolate (in
H. trigynum
to spatulate), similar to sepals in length or up to twice as long, spreading or ascending at anthesis, very little accrescent; sepals and petals not ciliate (appearing ciliolate in conjunction with overall surface indument).
Stamens
3 (aberrantly 4, in
H. boinense
H. Perrier
5) per petal, inserted between glands; anthers dorsifixed, broadly oblong-elliptical with oblong-elliptical locules and a large connective, the slits of dehiscence nearly parallel. Upper surface of
ovary
conical, usually shallowly, to nearly flat in flower, in fruit sometimes becoming convex; styles 3-5, free to base or near base.
Locule of fruit
subglobose (in
H. trigynum
ellipsoid and partly filled with spongy tissue), glabrous (sparsely pubescent); seeds sometimes 1 (to 2) per fruit, large and subglobose to ellipsoid (possibly at least
4 in
H. nobile
Baill.
).
Distribution.
–
Madagascar
.
Species included. –
Homalium boinense
,
H. brevipedunculatum
Scott-Elliot
,
H. capuronii
Sleumer
,
H. dorrii
Appleq.
,
H. graciliflorum
Sleumer
,
H. laxiflorum
,
H. maringitra
H. Perrier
,
H. nobile
,
H. oppositifolium
(Tul.) Baill.
,
H. pseudoboinense
Appleq.
,
H. pulchrum
Sleumer
,
H. randrianasoloi
Appleq.
,
H. ranomafanicum
Appleq.
,
H. schatzii
Appleq.
,
H. trigynum
.
Notes.
–
Sleumer (1973)
wrongly corrected the name of
Homalium
sect.
Eumyriantheia
to “sect.
Myriantheia
” and presumed it to have been based upon Thouars’
Myriantheia
. The two were not nomenclatural synonyms, but because he explicitly treated them as such, he effectively designated the same
type
for both simultaneously.
Homalium trigynum
has some unusual features that are similar to features common in sect.
Blackwellia
, which also occurs in
Madagascar
(see discussion above); molecular data regarding its relationships would be of interest. A recent revision describes five new species in the section (
Applequist, 2016
).