Pomaderris brevifolia (Rhamnaceae), a new species from south-west Western Australia

5 Pages·1994·1.3 MB·English

by  N G Walsh

POMADERRIS BREVIFOLIA (RHAMNACEAE), A NEW SPECIES FROM
SOUTH-WEST WESTERN AUSTRALIA
N. G. Walsh*
ABSTRACT
Walsh, N.G. Pomaderrisbrevifolia (Rhamnaceae), a—new species from south-west
Western Australia. Muelleria 8(2): 107-111 (1994). A new species Pomaderris
brevifoliaN.G.Walsh, formerlyincluded in P. myrtilloidesFenzl, is described and
illustrated. P. myrtilloides is circumscribed and contrasted with the new species.
INTRODUCTION
The name P. myrtilloides Fenzl has been applied to a varied assemblage of
shrubs, mostlyoccurringonlimestoneorlateriticsubstratesoronsanddunesnear
the southern coast ofWestern Australia, extendingfrom Albany eastward to near
Eucla on the South Australian border. P. myrtilloides sens. lat. has most readily
been distinguished from other Western Australian species of Pomaderris in
having flowers with narrow-linear petals. Other petaloid species of Pomaderris
in Western Australia have distinctly obovate or spathulate petals. Consider-
able variation in leaf shape, size and indumentum has been attributed to
P. myrtilloides, but field observation and examination of herbarium specimens
indicates the existence oftwo entities, readily separable on foliar, floral and fruit
characters.
TAXONOMY
Pomaderris brevifolia N.G.Walsh, sp. nov.
P. myrtilloideFenzl affinisfoliis parvioribus, crassis, margine recurvatis vel revolutis, inflores-
centibus et floribus minoribus, et sepalis persistentibus differt.
Typus: Western Australia, south-west, Susetta River, 34°00'S, 1 19°27'E, 13 July
1970, A.S.George 10000 (Holotypus: MEL; Isotypus: PERTH)
m
Slender shrub, to c. 1.5 high. Young branchlets, petioles and pedicels
coveredwithpale, short, semi-appressed silkyhairs. Stipulespaired, fusedtoward
mm
base, narrowly triangular, c. 1 long, silky pubescent on abaxial surface,
glabrous adaxially. Leaves shortly petiolate, lamina obovate, cuneate or obcor-
mm mm
date, 3-7 long, 2-4 wide; apex rounded, truncate or retuse, the midvein
commonly minutely exserted; lateral veins not apparent; upper surface smooth
andglabrous, orwith a lineofshort hairsalongtheimpressed midvein, or(rarely)
shortly hispid over the entire surface; lower surface densely covered by a mat of
fine stellate hairs, overlain by short appressed or slightly spreading simple hairs;
marginsthickened orrecurved to revolute, forminga conspicuousborderaround
mm
the lower surface. Inflorescenmceman umbel-like cyme, to c. 15 diam., with c.
10-20 flowers; pedicels 2-5 long, subtended by stipule-like bracts. Flowers
mm
cream to pale pink; sepals 1.3-2 long, silky pubescent abaxially, glabrous
mm mm
adaxially; petals linear to narrowly oblanceolate, 0.8-1.2 long, 0.1-0.3
wide, usually glabrous, sometimes with a few appressed silky hairs on the abaxial
mm
surface. Stamens shortly exceeding petals; anthers 0.3-0.5 long. Style 0.7-
mm mm
1 long, 3-lobed apically, the lobes to 0.3 long. Ovary summit densely
covered by short erect simple hairs, encircled by a raised glabrous rim. Capsule
mm
obovoid, 3.5-4.5 long, exserted for about 1/2 ofits length from the level of
* NationalHerbariumofVictoria,Royal BotanicGardens,BirdwoodAvenue,SouthYarra,Victoria,
Australia 3141
107
108
Fig. I, ^mnmeardefnr^n'sbreujo/ia. a — f-lowmeartiunrgebcraapnsc~uhlexx1.5be—-abcaoxcicaulssoufrfmaacteuorfelceaapfsxu5l,ewviitehweendlafrrgoem-
10000 (MEL), d-g from RD.°Dn.Sepencer 430(MEL). transverse section x5. a-c from A.S.George
tmrsueitr.tisoenedoffltahtetesneepdalosb,loobnsgc-uorveoliyd,5-c.an2glmedminlotnhge, lwoiwtehrapasrhto;rtsebpaaslaslpaerrils.is(tFeing.t i1n)
Representative Specimens (33 specimens examined)
o[C-f.M1t3 kDemsmNonNdW, SoEfRoaf(vRePanEvsetRnhTsotHrhpfoerSI,spEre2ao,5efl2iMM1taeAAyB.pagr1y.g96te13od9,6E..2y4,r25e0,4r.GJe5a>.li"Goeeftfosworaop4noed4.43f"46la6r(eP5sE,(^P1^E8^6R^3T,HM)a-xMwtelSlho(rMtELr)-iS4R“mEilAsieinpd,fce
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CAN ' National Park, Point Ann Rd. 8 Nov. 1989, R.D.Spencer 430 (MEL,
Distribution and Conservation Status
RangPeomeaadsetrwrarids btroevniefaorliMathaRsabgegeendriencloarnddedfrformomIsnreaaerliBtleuBfafyK.noUlnlliinkethPe Smtvirrtliiln-g
mlooirdees.inItlaanpdpe(ea.rgs. mtotohcecuStrirrlairneglyRavnegrey,nReaarvetnhsetchooarspteaannddoGcicburssonuparteoas5)0Ikt mdoeosr
109
not appear to be rare, and is represented in the Stirling Range, Fitzgerald River
and Cape Arid National Parks. (Fig. 2)
Habitat
Pomaderris brevifolia is an occasional component ofmallee scrub and open
heath, commonly on laterite-rich clay soils, amongst rocks or, less commonly, on
sandy substrates. Most occurrences are away from areas of direct coastal influ-
ence,themostnearlycoastalcollectionsbeingfrombesidelargeprotectedinletsor
estuaries (e.g. Beaufort Inlet, Wellstead Estuary, Gordon Inlet).
Etymology
The specific epithet ofthe new species refers to its small leaves, the smallest
ofany Western Australian Pomaderris and amongst the smallest known for the
genus.
Notes
Although closely related to the more widespread P. myrtilloides (which
extends along the coast from Albany almost to the South Australia border),
P. brevifolia is distinguished by its smaller leaves which have conspicuously
thickened, recurved or revolute margins. Variants of P. brevifolia with leaves
shortly hispid above have no equivalent in P. myrtilloides, although forms ofthe
latterexist with leaves eitherglabrous orstellate-pubescent on theadaxial surface
(see below). The inflorescences and flowers ofP. brevifolia are smaller. The few
fruitingspecimensofF. brevifoliaavailableshowthesepalstobepersistentinfruit
and the capsule exserted for about 1/2 its length, unlike fruiting specimens of
P. myrtilloides in which the sepals fall before the fruit matures and the capsule is
exserted for about 2/3 ofits length.
Most material ofPomaderris brevifolia at PERTH had been segregated from
P. myrtilloides and tentatively determined as "Pomaderris sp. 1’.
CIRCUMSCRIPTION OP POMADERRISMYRTILLOIDES
In the protologue of the species, Penzl (1837: 22) described the leaves of
P. myrtilloides as being under one inch {"folds uncia brevioribus'), obovate, with
apicesentireandroundedorretuse,glabrousontheuppersurfaceandwith dense,
short tomentum on the lower surface, stems and flowers. The inflorescence is
described as a small terminal corymbose cyme, and the flowers as having narrow,
linear-lanceolate, entire and bearded petals.
110
(1862: 69) described P. stenopetala from specimens collected by
Oldheldat Point Henry(nearBremerBay),agreeingwithFenzl’sdescription in all
but leaf shape (ovate to ovate-lanceolate) and dimension (2/3-1 1/3 inches).
Surprisingly, in his description he made no reference to Fenzl’s P. myrtilloides.
®^ntham s (1863: 419) description ofP. myrtilloidesgives the leaves varying
‘tfrom oboyate to obovate-oblong, very obtuse or almost acute, slightly emargi-
nate, mostly about 1/2 in. long, in the original specimens glabrous above and
• There is no reference to the petals being be.a.r.ded or otherwise as
noted by Fenzl and Mueller. Bentham’s description is followed by a brief diag-
nosis ot a new variety major, with ‘leaves larger, often 1 in. long; flowers larger’
equating it with Mueller’s P. stenopetala and citing the same type specimen.
obtus1ehoerttyrpuencsapteecaitmtehneaopfePx., m8y-r1t2ilmlomidelsonigsaantdwci.g4i-n7bmudm, wwiidteh,ogbloavbarotuesloenavtehse
adaxial suriace and with a dense indumentum of fine stellate hairs overlain by
short silky sirnple hairs on the abaxial surface.
MEL ofherbarium material ofP. myrtilloides at PERTH, CBG and
indicates a continuum of leaf and flower sizes from those represented by
the type through to those which would accord with P. stenopetala F.Muell.
l-P myrtilloidesyar. majorBenth.). Withintherangeofleafsizesexistspecimens
with leaves adaxially—glabrous and others with leaves finely stellate-pubescent on
the adaxial surface the latter form not hitherto included in descriptions of
P. myrtilloides. Specimens at PERTH with adaxially hairy leaves had been see-
regated as potentially an undescribed entity, but in the absence of other corre-
latingcharacters, I regardtheseasmerelyvariants.Thehabitatsandrangesofboth
variants appear to be largely overlapping, with the adaxially pubescent form
perhaps more common on deep sand and the adaxially glabrous form more
common on limestone-derived substrates.
rO\nl1y thosneomfeenactulraetsurwehiacnhddaifbfreirefsduebsstcarnitpitailolnyoffrPoommaPd.ebrrreivsifmoylritaialrleoiidnedsifcoaltleodw.s’
Pomaderris myrtilloides Fenzl in Endl. et ai, Enum. PI. 22 (1837). Type- ‘Ora
orientalis, Ferd. Bauer’; Holotype: W.
Oldfield.; Syntyp^e^s^^&opeItsaolsaynFt.Myupeelsl:.,KF(r2agshme.ets3):;6M9E(L18(622)s.heTetysp)e: Pt Henry
Pomaderris myrtilloides var. major Benth., FI. Austral T 419 18631
SyntMypes & Isosyntypes as above. f '
any-branmchmed shrub, from 0.3-2 m high. Stipules narrowly triangular to
subulate, 1-4 mmlong. Leaves shortly petiolate, lamina obovate, elliptic or
cuneate, 10-26 long 7-15 mm. wide; upper surface smooth and glabrous or
withalineofshorthairsalongtheimpressed midvein, orentirelycoveredbyamat
Iorfijmlionreustceencsetell.a5tm-e3m.h5aircsm; mdairamg.i;nspepdliacneel,s n3o-t8dmifmferleonntgi.atFeldoowenrsabcaxrieaalmstuorfpaacle.e
pink, sepals 2-3 long; petals narrowly lanceolate to oblanceolate, 1.3-2 mm
wXaploiobuwntobmgehue,rtsac0p22e.s^/n2/ht3t-o3,r0o^t.asf5nb^biaVaatmxssl^rais?llnaedtlnaewogrlicity0ldih...ed3^,fu«mrog/ouml^smambiltrnoh0oen.furg5sul-ie0tCov..aer8lpSmseomuoeflrdmieenfosllchaeotoronttvgmeio.mnoxenoSddtn,oyolfl4bye-tl4hos.1enp-5gas1-rme.osp5vaemllomsyi,ldmotn5ocg.-,lad2oneengnx5glssemeedlr3mty-ielndsloiobtflnehokg^edry
ACKNOWLEDGEMENTS
on ^ Rye ofPERTH for sharing hercomments and notes
RRooySalfRBontmanniinc rGa.rdens, Melbournes,pefcoirest,hteoirRcoogoepreSrpateinocnerwahinldeMoanrka Lcoeleleocfttihneg
ttrriipp,iannsdouttoh-MwaelsitMWoeisrtewrhnoAupsrterpalairae,dttohWeeasctceormnpMainnyiinnggPitllyusLttrdatfioornfunding^ the
REFERENCES
Bentham, G. (1863). ‘Flora Australiensis’. 1: 419. (Reeve: London.)
Mueller, F. (1862). FragmentaephytographiaeAustraliae. 3: 69.
Fenzl, E. (1837^ Rhamneaepp. 20-27, In S.L.Endlicher et al. ‘Enumeratio Plantarum’.
Manuscript accepted 18 May 1993