PARTXV I AREVISIO NO FONCINOTI SBENT H (APOCYNACEAE) A.P.M.DEKRUIF Department ofPlant Taxonomy Agricultural University Wageningen, TheNetherlands Received28-1-198 5 Dateo fPublicatio n17-VI-198 5 INTRODUCTION Thispublicatio n isa monographi c revision of thegenu sOncinoti s containing sevenspecies ,si xo fwhic h are restricted tocontinenta l Africa and onet o Mada­ gascar.Th estud y isbase d mainly onherbariu m material. Inadditio n the author has had the opportunity to study living plants of five species in the wild and undercultivatio n inbotanica lgarden si n Africa. HISTORY OF THE GENUS When BENTHAM (1849) described the genus Oncinotish e based it on a single species,O. nitida. Th enam eOncinotis i sderive d from the Latin 'uncus'(i nGree k 'OVKOQ'), 'uncinatus' meaning 'shaped like a hook, hooked', referring to the curvedtail so fth eanthers . Several authors added further species, some of which were later reduced to synonomy, while others have been referred to the closely related genusBaissea. Meanwhile a few specieswer eerroneousl y described in theclosel y related genus Motandra. In 1954 PICHON revised Oncinotisan d attributed 10specie s to it, 7 of which aremaintaine d here. GEOGRAPHICAL DISTRIBUTION The distribution of the genus is shown on Map A. Oncinotistenuiloba i s the mostwidel ydistribute d speciesreachin gfro m Western Nigeria to Eastern South Africa, O. glabrata, O. gracilisan d O.pontyi occur in West and Central Africa. Lesswidel y distributed species are:O. nitida,limite d to acomparitivel y narrow zone along the West African coast; O.hirta, restricted to Central Africa; and O. tomentella,endemi ci n Madagascar. HABIT AND GROWTH All Oncinotisspecie s are lianas or climbing shrubs. The present author has observed the architectural model of TROLL (HALLE & OLDEMAN 1970: 125; HALLE et al 1978:242 ) in the field for five species {O.glabrata, O.gracilis, O. nitida, O. pontyi and O. tenuiloba).Th e species wind either to the right or to theleft , orar eno t twining. FLOWERING SEASONS Oncinotisspecie s flower towards the end of the dry and the beginning of the rainyseasons ,an d fruits maturei nth edr yseasons . Agric.Univ. WageningenPapers 85-2 (1985) 1 RELATIONSHIPT OOTHE RGENER A Oncinotisi sclosel yallie d toBaissea an d Motandra. These3 genera constitute the subtribe Baisseinae of the tribeIchnocarpeae. The author will return to this subjecti nhi sforthcomin g revisionof Baissea. GENUS DIAGNOSIS Oncinotis Benth. 1849:451-452;Bentha m& Hooker 1876: 718;Baillo n 1889: 210; Schumann 1895a: 179; Stapf 1902: 220-224; Stapf 1907b: 512; Pichon 1948a: 196-197; 1950: 113-114; Phillips 1951:588 ; Pichon 1954: 9-36; Codd 1963:288;Dye r 1975:468;Markgra f 1976:222-223. Fig.A ; MapA Type species: O. nitidaBenth . Homotypic synonym: O. sect. Afrotis Pichon 1948:196. Heterotypic synonym: 0\ sect. MalgotisPicho n 1948: 197.Typ e species:O. tomentellaRadlk . Climbingshrubs o rlianas; whitelate xpresent . Branches unarmed. Branchlets opposite or subopposite, terete.Stipule s none.Leaves opposite or subopposite, thoseo fa pai requal ,withou tcolleter si nth eaxils ;petiol eofte n rounded beneath and channeled above when dry, otherwise terete, glandular along the adaxial side;blad eovat et oobovat eo rnarrowl yso ,usuall yacuminate ,sometime semar - ginate (or exceptionally rounded) at the apex, cuneate or rounded at the base, entire, sometimes undulate or recurved at the margin; midrib impressed above and prominent beneath; on each side 2-25conspicuou s secondary veins,whic h arecurve d towards themargin , anastomosing, impressed abovean d prominent beneath; often in the axils of some secondary veins domatia consisting of pits, often with a ciliate margin, or of a tuft of hairs; tertiary venation sometimes conspicuous, reticulate or scalariform. Inflorescences terminal or axillary, thyr- soid,rathe rlax ,many-flowered . Bracts,an d- ifpresen t- bracteoles,deciduous , insideglabrous ,ciliate .Flower s5-merous , fragrant, actinomorphic orwit honl y unequal sepals. Sepals imbricate, connate up to 1 mm at the base, subacute to obtuse at the apex, entire outside pubescent or with a dense tomentum, inside glabrouso ronl ysparsel ypubescen tnea rth eape xan dmargin ,ciliate ,exception ­ ally inside at the base 0-3 colleters per sepal, situated at the margin. Corolla: tube outside shortly pubescent, exept the portion, covered by the sepals,insid e glabrous,excep tfo rtuft s ofstif fhairs, alternatin gwit hth estamens ;a tth emout h of thecoroll a tube with 5alternipetalou s corona scales;lobe s in bud contorted and overlapping to the right, obtuse to subacute at the apex, recurved, entire, glabrous inside, slightly ciliate. Stamensincluded , connivent into a cone;fila­ mentsabaxiall y glabrous,adaxiall y pubescent; anthers introrse, fusiform, basi- fixed, acuminate, sagittate at the base and at both tips provided with a subglo- boseincrassatio n whichi su pt o0. 1 mmi ndiameter ;cell stwo ,discrete ,parallel , dehiscent throughout by a longitudinal slit; below the fertile part inside on the 8 Agric.Univ. WageningenPapers85-2 (1985) i\k^ >:-i •'•''. r'-'y4}: •;• • r**~ • . • . • . ^ v- •.^.'^ ;.•' /' 1 V "AJV , • • w* -i*""• • • H^lZ*' I. •'*.'." * . ^": iZ.^zr. ¥\ „_J / •'" •:**? 'T ' . *^.' • • ***- **v . ' ' . .'..'•!•.. - t>^l 55^- :•" & ^i^R^yPSb*; ^rj^jjBB * • /ft\ . • & * ^1^-,'i -V •V ••!.;•;•; *n**ei~—»"^»*—*• .•.•"•.'i.'-v?.-''.^--''1;:; ••:-:.^.iS'-1''•*•••.•.::,; : "V ..I;'/ * ;. ';. • . '..v v^«s. sir -M-mfc^ •' • •••--...•• .i. FIG. A. Leaf baseswit h petiole from above (2.7 x) and domatia (27 x); thenumbe r corresponds with the species number in this revision. (1. De Kruif 663; 2. De Kruif 659; 3. Gerard 5497; 4. DeKrui f701 ; 5. DeKrui f666 ; 6. Drummond 10187;7 .Decar y5298) . Agric. Univ. WageningenPapers 85-2 (1985) c <u CQ •5 •S «-» s: O C/) 3 C o<U .c *-» «*o- c #o 3 •c *-> < s< 10 /Igr/c. £//i/v. WageningenPapers 85-2 (1985) connective a nearly oblong patch, the retinacle, 0.1-0.4 x 0.05-0.1 mm, with minute hairs along the margin, adhering to the pistil head. Pistil: ovary hemi- inferior; carpelstwo ,connat ea tth eextrem ebas eonly ,ovoid ,laterall ycompres ­ sed,entirel yo ronl yapicall ydensel ypubescent ;abruptl ynarrowe dint oth estyle , surrounded by a disk, adnate to the ovary at the base only, which iscompose d of a ring and 5lobes , alternating with the stamens; style obconical to almost cylindrical, composed of two connate strands, glabrous; pistil head glabrous, consisting of a slightly 5-winged upper and a cylindrical lower portion, to the latter ofwhic h the5 retinaclesadhere ;pisti lhea d at theape xwit h twoappendi ­ ces, united at the base, glabrous. Placentas adaxial, ovuliferous at the abaxial side only. Fruitspendulous , composed of two (sub-)equal follicles, often re­ curved or upcurved, connate at their extreme base, dehiscent along an adaxial lineo fdehiscence ,fusifor m tonarrowl ycylindrical ,a t theape xacute ,an dwhe n dry often curled, or obtuse; exocarp woody and at the outer surface smooth, sulcate,longitudinall y winged;endocar p stiff, thinly pergamentaceous, smooth inside. Seedsattache d to the adaxial side of the fruit, with at the apex a dense tuft ofsimpl ehair s(coma) ,directe d towardsth eape xo fth efruit ; grain laterally compressed, convex at one side and concave at the other, elliptic to oblong, glabrous, subacute to obtuse at the base, truncate at the apex, subundulate at themargin , with thehilu m at theape xan d witha raphedescendin g to thebase ; testa very thin; endosperm fleshy, in a thin layer completely surrounding the embryo; embryo straight; cotyledons first complicate, later unfolded, ovate to elliptic, at the base cordate, rounded or cuneate, at the apex acute, glabrous on both sides,wit h 3-10 secondary veins; rootlets terete, rounded at the apex, glabrous. Distribution:? speciesi nTropica lAfric a inclusiveo fMadagascar . Note: The sections proposed by PICHON (1948a) and later rejected by him (1954)a sartificial ,ar eals ono tmaintaine d hereb yth epresen t author. KEY TO THE SPECIES 1. Domatia absent or inconspicuous and consisting only of a tuft of hairs (see fig. A:2 an d3) ;branchlet sneve rglabrou s 2 Domatia usually present and consisting of pits with or without hairs along themargi n(se efig. A :1,4,5, 6an d7) ;branchlet shair yo rno t 3 2. Leavessparsel ycovere dwit hsimpl ean d (lessoften ) branched hairs;domati a consisting of a dense tuft of orange-brown simple bairs; petiole densely covered with simple and (less often) branched chairs, along the adaxial sidewit h 1-5 glands and near the base of the blade with at least 1,some ­ times2 pairso fgland s(se efig. A :2) ;coroll a 5.3-9.1m mlong ;lobe s 1-2.4 x aslon ga sth etube ;follicle s shortly rustybrown-pubescent . West and Central Africa 2.0.gracilis Agric. Univ. WageningenPapers 85-2 (1985) 11 Leaves very densely covered with variously branched hairs; domatia very inconspicuous and consisting ofsom eshor t simple or variously branched hairs; petiole very densely covered with variously branched hairs, along theadaxia l sidewit h 1-15 glands and near thebas e ofth eblad ewit h 1-8, mostlyonl y2 glands(se efig. A :3) ;coroll a 4.1-5.9m mlong ;lobe s0.7-1. 1 x as long as the tube; follicles covered with an up to 2.5m m thick,deci - duousdens erust ybrow no rgre ytomentum .Centra l Africa . 3.0.hirta 3. Leaveswit hinconspicuou stertiar yvenatio nbeneath ,dul lan ddistinctl ypale r than above;leafblad e obovate and often emarginate at the apex; follicles narrowlycylindrical .Wes t and Central Africa 5.O.ponty i Leaveswit h conspicuous tertiary venation beneath, glossy and only slightly palertha nabove ;follicle snarrowl ycylindrica lo rfusifor m 4 4. Secondary veins strongly curved and shaping an angle of 10-35(-40)° with themidrib ;pit swit h adens e tuft of hispid hairs along themargin ; petiole puberulous or pubescent, along the adaxial side with 2 pairs of glands, usuallyon epai rnea rth ebas eo fth eblad e(se efig.