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热带亚热带植物学报 2002，10(4)：301—305 ；
Journal of Tr~ical and Subtropical Boumy l
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托叶铁科(苏铁 目)羽片脉序和羽片解剖学研究 I
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谢 中誉 唐源江 刘 念 吴七根 廖 景平 ；
fIlIlq羊：} l旄华』打十』．1物 f ( ，J。。力 J’ -lJ 510650) I
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摘要：详细研究了托 饮科 属的2利l1 农 物．Stmgeria eriopu．s年¨Bowenia serubaa f 爿爿"儿水 I
序和羽片解剖 。 个 (dL器特 』 J ‘输 钐 ‘ 极为年¨似 ， C孔的分 、爿爿" l
脉序式样J．j叶缘形态、 i液道的 f尢、 绵 织 栅 绑【纵 分化、J ， ^ 【钐 j 戊 胞,It l
川 特征办嘶~!qfi-较人的篪片。将返J{． 特 ：铁科年lI洋米铁科作 r比较 ， 论 ．r返 特 l j
系统学 l 的意义。 f究 支持 Stevenson(1992)将 $q-5}-为 、l 干斗以及托II饮科址介 J ：铁科 l
j泽米铁科之 的脱 。 j
关键词 ：托叶铁科：爿爿"爿爿儿水；爿爿" 削
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中图分类号：0944．5 文献标识码：A 文章编号：1005-3395 f2002)04-0301-05 l
Venation and Anatomy of Pinnae in Stangeriacea(Cycadales) i
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XIE Zhong-yu TANG Yuan-jiang LIO Ni 8．1" WU Oi-gen LIA0 Jing-Ping‘ l
(,South China，ml 眦e Boumy，the Chine．~e Actulemy Scieru：es，Guangzhou 510650，China) l
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Abstract：Pinna venation pattern and pinna anatomy of two species，Sumgeria eriopt~and i!
Bowenia serulata，representatives of the two genera in Stangeriaceae were studied in this paper． i
The two species (genera) are similar in stomatal character and in the absence of accessory l
transfusion tissue，but they are very different in stomatal distribution，pinna venation pattern and
pinna marginal shape， presence or absence of m ucilage canal， differentiation of palisade and
spongy parenchyma， characteristics of girder parenchyma and epidermal anticlinal wal1． Pinna
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venation and pinna anatomy of Stangeriaceae are compared with those of Cycadaceae and l
Zamiaceae． Stevenson’S classifcation r 1 992) with two subfamilies and the treatment of l
Stangeriaceae as a transitional evolutionary position betw een Cycadaceae and Zamiaceae is l
supposed by present study． l
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ey words：Stangeriaceae；Pinna venation；Pinna anatomy l
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1 Introduction
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Johnson⋯separated genus Stangeria T． Moore from Zamiaceae and set up family l
Received：2001—12-31 Accepted：2002-04-24 l
Foundation item：National Natural Science Foundation of China(30070062)；The Key Project of the Chinese Academy I
of Sciences(KSCK2-SW一1 O4J：Guangdong Environment Protection Bureau(970 1 65) i
Corespndig author l 蚕
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Stangeriaceaewithonegenus,Stangeria(with1species).BoweniaHookerexJ.D.Hooker(with
2species) wasincludedinZamieae,oneofthethreetribesofZamiaceaeinhisclassifcation.
Subsequently,basedontheparallel-veinedpinnaeinBoweniaHookerexJ.D.Hooker,Stenvenson~
hadeverremovedBoweniafrom Zamiaceaeandestablishedanew family,Boweniaceae, an d,
Stangeria was included in thisfamily.However, in hisnew classification[34],Boweniaceae
wasreduced tosubfamilylevelwithin Stangeriaceae. Both Cran e[~ an d Stevenson[4]putthe
monogenericCycadaceaeasthesistertaxonofallotherextantcycads,an dbelievedthatStangeria
an dBoweniaformeda cladethatwasasistertaxonofZamiaceae.Althoughnear thirtycharacters
wereusedbyStevensoninhiscladisticanalysis[3],man ycharactersofvegetativeorgan an atomy,
whichprobablyhad importantsystematicsignifican ce, such asthepinnavenationpattern an d
an atomicalfeatures,wereneglectedinhiswork.
Hitherto, thevegetativeorgan s, wholly orinpart, ofStangeriaceaehavebeen studied
anatomically[6-~], however comprehensive investigation on venationpatern an d an atom ical
featureofthetwogenerainStangeriaceaeisstilllimited.Inthispaper,pinnavenationpatern an d
pin aanatomyoftw ospeciesrepresenting tw ogeneraofStangeriaceaearedescribedandtheir
systematicsignifican cesarediscusse&
2 M aterialsandmethods
M aterialsofStangeria eriopus an d Bowenia serrulata were obtained from livingplan ts
cultivatedinSouthChinaBotanicalGarden(SCBG).Pinnaefromthemiddlepartoffrondwere
fixedinFAA an dsectionedwithslidingmicrotome. Crosssectionsof15-30t~m thicknesswere
takenandduplicateslideswerestainedwithEhrlichhematoxylin, dehydratedwithalcoholseries
an dclearedbyxylene, andfinallymountedinneutralbalsam . Allsectionswereexaminedan d
photographedun derLeitzOrtholuxII.
3 Results
Anatomicalcharacteristicsofpin aeofStangeriaceaeareshown in Table 1an d detailed
pin aan atomyisdescribedasbelow.
3.1 Characteristics of venation
Pin a venation is ofdichotomousparallelvein in both Stangeria eriopus an d Bowenia
serrulata,butmidribwithfourparalelvascularbundlesexistsonlyinStangeriaeriopus(PlateI:
I).Dichotomousveinletendingsconecteachother,orendatthemarginofpinaoratserratures
inStangeriaeriopus(PlateI:I,6),whilethoserunstraighttotheserraturetip(PlateI:II)in
Bowenia serrulata.
3.2 Anatom icaldescription
Epidermal cells The epidermis ofpinna is heavily cutinized in the tw o species
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第 4期 谢 中誉等：托叶铁科(苏铁 目)羽片脉序和羽片解剖学研究 303
examined， and both of the upper and lower epidermis consist of one layer of epiderm al cells
(Plate I：2，3，7，8)．Some ofthe epidermal cels contain druses．
Epiderm al cells are irregularly polygonal in shape， 90 Bm ×70 Bm to 250 u m ×20 Bm in
size， an d an ticlinal wall is undulate in Stangeria eriopus； while in Bowenia serrulata epiderm al
cells are iregu larly rectangu lar in shape， about 260 Bm × 15 Bm in size， an d an ticlinal wall is
straight(Plate I：9、．
Stom ata Stomata are restricted to lower epiderm is an d cyclocytic with a T—shaped
thickening atthe pole region in Stangeria eriopus (Plate I：4)．Accessory cels are about 5-6 in
number and irregular in shape．The size ofstomata is about 80 la m x80 la m in diam eter(Plate I：
5、． Encircling cells overlapping the stomata are raised to form a flat rim， which appears at the
same level as other epiderm al cells．
In Bowenm serrulata,stomata are actinocytic with arch—shaped thickening at the pole region．
Accessory cells are iregu lar in shape an d about 4—6 in num ber． Stomata are densely distributed
on lower epiderm is， while sparsely on upper epiderm is an d are restricted to the bases of the
pinnae．Th e encfcling cell rims are flat an d are located at the same level as other epiderm al cells．
Stomata are about 100 um×60 um in size(Plate I：7，8)．
Hypodermal sclerenchyma cells In pinna margin, hypoderm al sclerenchyma appears
as 2-3 layers ofcels in thickness beneath upper and lower epiderm is in Stangeria eriopus(Plate
I：21，while those as 1 layerinBowenia serrulata (Plate I：8)．In midrib region ofStangeria
eriopus，as described by Alice Lambt8]，1-3 layers of sclerenchyma cells occur beneath upper an d
lowerep idermis， an dare scattered in groupsthroughthenarrow regionsintern altotheupperan d
lower epidermis，and singly through the rest ofthe midrib(Plate I：1)．
M esophyH In Bowenm serrulata,both palisade an d spo nge tissues are not diferentiated
in mesophyll,an d some idioblastic cells are sparsely distributed am ong parenchyma cells rPlate I：
71．Whereas in Stangeria eriopus，palisade cells are diferentiated and slightly elongated,often
closely arranged in two layers beneath upper epiderm is；spo ngy cells are irregu larly arranged an d
elongated with apparently intercelular space(Plate I：3)．
Vascular bun dles are collatera1． Phloem is regu lar in Stangeria
eriopus．but iregu lar in Bowenia serrulata．Fibre cells form abaxial an d adaxial“caps’ which
con ect、^，ith both abaxial an d adaxial epiderm is and term ed as girder parenchyma in Stangeria
eriopus(Plate I：21．However,girders are absent in Bowenia serrulata(Plate I：7，8)．Accessory
tran sfusion tissue is absent in both species／genera．
M ucilage cannals M ucilage canals and scleren chymatons cells are present in midrib
regi0n(PlateI：11inStangeria eriopus，andabsentinBowenia serrulata．
Sclerenchyma cells at pinna m argin Sclerenchymatous cells are arranged in 2—_3
layers within pin amarginin Stangeria eriopus，butin onelayerin Bowenia serrulata．
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热 热带 }^物 学报 第 1O卷
Table 1 Anatomical comparison of pinna characteristics between Stangeria eriopus and Bowenia serrulata
4 Discussion
Stangeria eriopus and Bowenia serrulata are very similar in stomata． M oreover, accessory
transfusion tissue is absent in these two species／genera．However,they are quite diferent in pinna
venation pa~em，marginal shape，diferentiation of palisade and spongy tissues，characteristics of
epidermal anticlinal wall and the absence or presence of girder parenchyma and mucilage canals
in midrib(Table 1)．These evidences strongly support Stevenson’S classifcation of Stangeraceae
with two subfamiliesI 1．
Epiderm al anticlinal wall is undulate in Stangeria but is nearly straight in Bowenia, and
straight in family Cycadaceae as wel1． Genus Bowenia， on the other hand， shares some
characteristics with some species of Zamiaceae， such as Mcrozamia moorei， with stomata
distribution on both adaxial and abaxial epiderm is(Tang，Liu，Xie，Wu and Liao，unpublished)．
According to our studies， the evolution of mucilage canals in midrib in Zamiaceae have a
tendency from numerous to a few， and that of sclerenchyma cells from unobvious to obvious．
Present investigation shows that both mucilage canals and sclerenchyma cells are present in
midrib in Stangeria，but absent in Bowenia．It is interesting that mucilage canals are also observed
in some species of Zamiaceae It21．Based on these features．it iS likely to be reasonable to assume
that Stangeria has a close relationship with some taxa ofZamiaceae．
The venation pattern is characteristic and constant for each taxon of Cycadales，and has been
considered to be a diagnostic feature at the family level㈣ ． In comparison with the known pinna
venation patterns of Cycadaceae and Zamiaceae，an interesting result can be found,i．e．venation
patterns of the tw o genera of Stangeriaceae are apparently transitional features betw een
Cycadaceae and Zamiaceae．For example，the venation ofBowenia iS more similar to that ofmost
species of Zamiaceae (except Chigua) because they have no midrib， while that of Stangeria is
more similar to that of Cycadaceae which has midrib．In addition，midrib in Sttmgeria consists of
4 parallel vascular bundles， which is also regarded as a transitional feature by present authors，
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第 4期 谢中誉等 ：托 叶铁科(苏铁 目)羽片脉序和羽片解剖 学研究 305 I
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because there is one main vascular bundle in midrib of Cycadaceae， but Zamiaceae has parallel l iveins．
In our latest unpublished studies，as well as previous investigation[H】，it is not difficult to find l
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out that the accessory transfusion tissue is well developed in Cycadaceae but it is absent in
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amiaceae【 ． Accessory transfu sion tissue of Stangefiaceae is also absent absolutely
． This l j
diference sems to implicate that the acesory transfusion tisue has an evolutionary tendency l f
rom present to absent in these three families． Therefore， according to present investigation on 。I
pinna venation and anatomy，the characters concerned more strongly suppo~the treatment of l
Stangeriaceae as a transitional evolutionary position between Cycadaceae and Zamiaceae[4]
。 l Acknowledgements We thank Mr．Chen Ze—li an and Ms
． Ca i Xue．zhen for the i r
kind help and assi stance in the preparat ion of the sl ide specimens and photos． l
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References： l
【l】Johnson L S．The families ofcycads and the Zam iaceae ofAustralia ．Proceedings ofthe Linnean Society ofNew South l Wales，195，84，Part I：64—1 7．
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【2】Stevenson D W．Observations on ptyxis，phenology,and trichomes in the Cycadales and their systematic implications【J】．
AmerJBot，1981，68(8)：l104-1ll4．
【3】Stevenson D W．Morphology and systematics ofthe Cycadales【J】．Mem New York Bot Gard,1990，57：8-55． i
【4】Stevenson D W．A formal classifcation ofthe extant cycads【J】．Britonia，1992，44(2)：220—223． ；
【5】Crane P．Major clades and relationships in“higher”gymnosperms【A】．In：Beck C．Origion and Evolution ofGymnosperms l
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【M】．NewYork ColumbiaUniversityPres，198．218—272． l 【6】Worsdel W C．The anatomical structure ofBowenia spectabilis Hook【J]．Ann Bot(London)，1900，14(53)：159—160． I
【7】MarshA S．Notes on the anatomyofStangeria paradoxa【J】．NewPhytol，1914，13(102)：18—30． I
【8】Alice Lamb S M．Leaflets ofCycadaceae ．Bot Gaz，1923，76：185—202． l 9WangY Z
， Chen J R．Leaflet epidermal characters of the Clyc∞in Chma and their taxonomic signifcance【J】．Chinese Bull I
Bot，1995，12：47—51． l
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【10】NorstogKJ，NichollsT J．Th eBiologyoftheCycads【M】．Ithaca,USA：CornellUniversityPress,1997．33—100． }
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【ll】Liao JP，YangQF，Wu QG，et a1．Morphology andanatomyon Clyc∞ in Chma【A】．In：WangF X，LiangH B．C如∞ in I
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China[M】．Guangzhou：ScienceandTechnology Press,1996．143-189．
【12】BrashierC k Vascularizationofcycadleaflets【J]．Phytomophology,1968，l8(1)：35-43． l
Explan ations ofplate l l
PlateI l 1-6：Stanger／a eriopm：7-l：Bowen,ia serulat．Uper sideisadxial surfaceofpinaeinplateI：l，23and7．1：Apart
ofpinnae through midrib in transverse section,showing vascular bundles(white arrow)and the mucilage cannals(black arrow)in l
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the midrib，x32；2，3：Parts ofpinnae in transverse section，x 84．4：Upper epidermis in surface view，x 340：5：Lower epidermis l
in surface view，showing stomata,x 340：6：Pina venation，x 2．8；7：Part ofpinae in transverse section,x 130：8：Part of l pnae intransvere section,x 64
． 9：Upper ep idermis in surface view,showing stoma ta，x 340：10：Lo wer ep idermis in surface
view，showing stomatal apparatus，x 340：ll：Pinna venation，x 2．8． i
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