《园林树木学西农--吉文丽》第一章.ppt

pandectChapter1TaxonomyandClassificationofLandscapetrees 2periods MethodsofClassification NaturalclassificationArtificialclassification Taxonomy 分类学 theclassificationoforganismsinanorderedhierarchicalsystemthatindicatesnaturalandevolutionaryrelationshipsbetweenthem naturalclassificationClassification 分类 accordingtothefunctionofwoodylandscapeplantsinurbangreening artificialclassification Asweknow thereareabout8000woodylandscapeplantsinourcountry Ofthese 3000specieshavebeencultivated Wealsointroducedmorethan1000cultivarsfromforeigncountry Morethan2000speciesinXishuangbannabotanicalgardenarecollected butonlyseveralhundredsspeciesareappliedtourbanarea Inordertogrowmorewoodyspeciesinlandscapearchitecture weshouldknowthenames characteristicsofwoodyplantsfirst Correctplantisveryimportantforapplication Itisworseandmoredangeroustopeopleforusingwrongplantsasfood Forexample 木本香料并做调料品的八角和莽草都是同科 八角科 同属 八角属 的常绿乔木 形态很相似 八角的聚合果8 先端钝尖或短尖 莽草聚合果10 13 先端是细长弯曲的尖头 如不能正确区别 误食莽草可置人于死地 所以需正确鉴定 进行分类 Wewillreviewtheprinciplesofsystematicclassification theplantnomenclature andkeysfirst thenlearnhowtoconstructandusedichotomouskey 分支式检索表 分类学 taxonomy 可以定义为研究和描述有机体的变异 探讨这种变异的因果关系 并运用所掌握的资料去建立某个分类系统的学科 分类学和系统学 systematic 这两个术语现在常被不严格地作为同义词并用 如果要说两个术语有些什么不同的含义 那么分类学常用来指分类理论和实践 包括它的基础 原理 步骤和规则 而不是它的最终产物 分类系统 系统学是有机体的种类和多样性以及它们间全部亲缘关系的研究 simpson1961 比分类学含义多少宽广些 Theprinciplesofsystematicclassification 系统分类的基本原则 Systematics 系统分类学 thestudyofrelationshipsoforganismsandevolutionaryprocesses Thetaxonomicorganizationofspeciesishierarchical Eachspecies Prunuspersica桃 forexample belongstoagenus Prunus桃属 李属 樱属 梅属 eachgenusbelongstoafamily Rosaceae蔷薇科 eachfamilybelongstoanorder Rosales蔷薇目 eachorderbelongstoaclass Dicotyledoneae双子叶植物纲 eachclassbelongstoaphylum Spermatophyta种子植物门 andeachphylumbelongstoakingdom Plantae植物界 Conceptofspecies物种的概念 大家所接受的概念是 种是自然界中客观存在的一种类群 这个类群中的所有个体都有着极其相似的形态特征和生理 生态特性 个体之间可以自然交配产生正常的后代而使种族延续 它们在自然界中占有一定的分布区域 人们就以这种客观存在的类群称为种 也是作为分类的基本单位 Homeworkhttp sorrel humboldt edu kll1 speciesdef html ImportantPlantClassificationTerminologyGenus Weaklydefinedasagroupofplantscontainingoneormorespecies Thespecieshavemorecharacteristicsincommonwitheachotherthantheydowithspeciesofothergenerainthesamefamily Similarityofflowersandfruitsisthemostwidelyusedfeatureofcomparison Agenusmaycontainasinglespecies e g Ginkgobiloba ormorethan100 e g Rosaspp Thepluralofthesingulargenusisgenera Species Agroupofindividualplantsthatarefundamentallythesame separatedfromothercloselyrelatedspeciesby distinct morphologicaldifferences Allindividualsinagivenspeciesarenotidentical butcanexpressvariationincertaintraits Speciesisabbreviatedsp singular orspp plural Variety Apopulationofplantswithinaspeciesthatdisplaycleardifferences differencesthatoccurinnaturalpopulations Avarietynameiswritteninlowercase italicizedorunderlined andprecededbytheabbreviationvar Forexample HoneylocustisGleditsiatriacanthoswhereastheThornlessHoneylocustisGleditsiatriacanthosvar inermis Latinforlackingthorns Subspecies abbreviatedssp isforpracticalpurposesequivalenttovariety Forma Describessporadicvariations suchasanoccasionalwhitefloweredplantinapopulationofanormallyred floweredspecies Forexample QuercusglaucaThung 青岗栎 isusuallybigleavesinnature butsmallleavesplantsoccurnaturally beingreferredtoasQuercusglaucaThung f gracilisRehd et Wils 小叶青岗栎 Cultivar AtermcoinedbyLibertyHydeBaileyandderivedfromtheterm cultivatedvariety Itisdefinedasanassemblageofcultivatedplants whichareclearlydistinguishedbyoneormorecharacters andwhichwhenreproduced sexuallyorasexually retainsitsdistinguishingcharacteristics AyellowstemformofRedosierDogwoodisCornussericea Flaviramea 金枝梾木 Thecultivarnameisnotitalicizedorunderlinedandhassinglequotesoneithersideofthename Cultivarisabbreviatedcv sotheplantcouldalsobenamedwiththesinglequotesdeleted suchas Cornussericeacv Flaviramea Hybrid Thisisaplantthathasoriginatedfromacross orhybridization betweentwospecieswithinagenera InterspecificHybrid ortwodifferentgenera IntergenericHybrid Thesmallmultiplicationsign x usedbetweengenusandspecificepithetnamessimplyindicatesthattheplantisaninterspecifichybridorigin Example Abeliaxgrandiflora Anintergenerichybridiswrittenwithalargemultiplicationsign X beforethegenusname Example XCupressocyparisleylandii 1 种的学名如 银杏GinkgobilobaL 多为名词多为形容词命名人缩写2 变种的学名 在种名之后加上Var varietas 符号再加上变种词如 樟子松是欧洲松的变种PinussylvestrisLinn var mongolicaLitr 欧洲松变种符号变种加词常写为Pinussylvestrisvar mongolica3 变型的学名 f forma 小叶青岗栎QuercusglaucaThung f gracilisRehd et Wils 符号变型加词 PatentsandTrademarks Patentsgiveexclusiverightsandprotectiontoaninventortomake use andsellaninvention For20yearsafterthedateindicatedonaplantpatent onlythepatentholdermaycommerciallyraiseorsellapatentedplant Othersmaydosothroughlicenseorroyaltyagreementswiththepatentholder Trademarksprovideanotherformofprotection Theplantnamecanbetrademarkedandsuchnamescannotbeusedasanameforanyothersimilarplant Trademarkedplantnamesareindicatedbyuseofatrademark suchasBetulanigraHeritage whereaspatentedplantsaredesignatedwitharegisteredtrademark Confusingtosomeisthefactthatpatentedcultivarsmustbegiven inadditiontotheregisteredtrademarkname anofficialcultivarnameregisteredaccordingtotheInternationalCodeofNomenclatureforCultivatedPlants ICNCP国际栽培植物命名法规 InthecaseofBetulanigraHeritage theactualcultivarnameapprovedbytheInternationalCultivarRegistrationAuthorities ICRAs国际品种登录权威 isactually Cully PlantRecognitionLearningtorecognizedifferentkindsofplantsinthenurseryandlandscapeisanimportantskillthatrequirescloseobservationandknowledgeofplantparts Landscapeornamentalsvarygreatlyinoverallshapeandhabit rangingfromsprawlinggroundcoverstomoundingshrubs tocolumnartoweepingtrees Evenwhenthegeneralshapeissimilar landscapeplantscandifferinnumerousothertraits includingtheshape color andsizeofleaves flowers andfruits andthecolorandtextureofbarkandtwigs Notwithstanding knowledgeofthesecharacteristicsalonemaynotbeenoughtoclearlyseparateonetypeofplantfromanother especiallywhenenvironmentalorculturalfactorslikepruninghavealteredtheplantsnaturalformandgrowth ortheplantisveryyoungorold Forthesereasons additionalmorphologicalfeaturesoftenneedtobeexaminedforaccurateplantidentification likeleafarrangementandtype andleafshape andleafapices leafbases leafmargins typeofleafvenation shapeofleafscarsandvascularbundles terminalandlateralbudshape size andcolor andflowerandinflorescencemorphology 3分类系统上的等级 以桃为例 界 植物界门 种子植物门亚门 被子植物亚门纲 双子叶植物纲亚纲 离瓣花亚纲目 蔷薇目亚目 蔷薇科亚科 李亚科属 梅属亚属 桃亚属种 桃 BiologicalsystemofLinnaeus TaxonomicSystem Intheformalnomenclatureofanyspecies livingorfossil taxonomistsfollowthebiologicalsystemofLinnaeus KingdomPhylum phyla ClassOrderFamilyGenus genera SpeciesSubdivisions Sub 亚 super 超 PlantNomenclatureIntroductoryCommentsTheoverallobjectiveofthislectureistohelpyoulearnaboutplantnomenclatureandclassification Theinformationpresentedhereprovidesanimportantfoundationforfuturelearningaboutlandscapeplants Youwilllearnprinciplesthatgoverntheproperwritingofscientificnames i e Latinbinomial skillsthatareessentialforcommunicationwithinthelandscapeindustry Youwillalsobecomefamiliarwiththescientificbasisforclassifyingplantsintodistinctgroupings Spendtimeputtingasmuchofthisinformationaspossibletomemorybeforemovingon Binomialnomenclature 二名法 双名法 Eachspeciesisdefinedbytwonames thegenericandspecificnameswithLatin Infulltaxonomicnomenclaturetheauthor snameandthedateofthepublicationaregivenafterthespecies e g SquamulariagrandlisChao 1929Genericname Specificname Author sname DateBothgenericandspecificnamesinitalic Lawofpriority 优先律 Allthenomenclatureoforganismsfollowthelawofpriority Thefirstpublishednameisvalid PlantNamesPlantscanbedescribedusingdescriptorssuchastree shrub vine groundcover evergreen deciduous annual perennial woody herbaceous hardy tender etc Singleworddescriptionsliketheseareusefulbutcontributeonlylittletoseparatingoneplant kindfromanother Forexample manyquitedifferentplantscouldallbereferredtoastrees Morethoroughdescriptionsusingmanywords aswasdoneinearlyscientificnamingsystems aretoocomplexandcumbersomeforcommonusage Today eachplantkindisgivenauniquescientificname CarolusLinnaeus inhisSpeciesPlantarum 1753 firstdevelopedthescientificsystemwenowusetonameplants referredtoastheLinnaeanBinomialSystemofNomenclature Usingthissystem plantsaregiventwoLatinizednamesthatcreateabinomial IntheLatinbinomial thefirstnameiscalledthegenusandthesecondiscalledthespecificepithet Thegenericnameandthespecificepithetcombinetoformthespeciesname Forexample thespeciesnamefortheNorthAmericanSugarMapleisAcersaccharum TheLatingenusAceristheancientLatinnameformaple perhapsmeaninghardasisthewood whereasthespecificepithetsaccharumislatinforsugarorsugarcane SincefewpeoplespeakLatin anobviousquestionmightbe whynotsimplyusecommonEnglishnames likeSugarMaple insteadofscientificLatinnames Theprimaryproblemwithcommonnamesisthattheyareoftencommonlyusedinonlylocalizedregions Forexample theSugarMapleisoftencalledRockorHardMapleindifferentpartsoftheUnitedStates TheAmericanHornbeam Carpinuscaroliniana isalsocalledBlueBeech Musclewood WaterBeech orIronwoodinvariousregions DirrnotesinhisManualofWoodyLandscapePlants 1998 thattheEuropeanWhiteWaterlily Nymphaeaalba has15differentcommonEnglishnames 44French 105German and81Dutchnames atotalofover245commonnames Tocompoundtheproblem identicalcommonnamesindifferentregionsoftenrefertocompletelydifferentplants Thepotentialforconfusioninthecommunicationsbetweenpeoplelivingindifferentgeographicalregionsisobvious Tostandardizeplantnamesaroundtheworld asinglespeciesname aLatinbinomial hasbeenestablishedforeachplantaccordingtotheInternationalCodeofBotanicalNomenclature ICBN bytheactivityofauthoritiescoordinatedinpartthroughtheInternationalAssociationforPlantTaxonomy IAPT TheregisteringofculivarnamesistheresonsibilityoftheInternationalCultivarRegistrationAuthorities ICRAs 国际植物命名法规InternationalCodeofBotanicalNomenclature ICBN 一种植物只能有一个合法的名称 其它名称都作为异名 一种植物若有几个名称 应按优先律 最早发表的为合法名称 处理 所有植物名都要用拉丁名或拉丁化的名称 给每种植物命名 必须有模式标本 合法名称的成立必须在正式国家刊物 杂志 著作发表 必须有拉丁文记载 中名的命名原则 一种植物只应有一个全国通用的中文名称 至于全国各地的地方名 可任其存在而称为地方名 中文属名是植物中名的核心 在拟定时选择使用广泛 形象生动与形态 生态 用途有联系的中名作属名 名称中尽量避免迷信色彩及纪念古人或今人的名称 目前还存在混乱 WritingaSpeciesNameThespeciesname i e Latinbinomial isitalicizedorunderlined Thefirstletterofthegenusisinuppercasewhereasthespecificepithetisinalllowercaseletters Asanexample thespeciesnameforSugarMapleshouldbewrittenas AcersaccharumorAcersaccharumAnameoftenfollowingtheLatinbinomial asinAcersaccharumMarsh istheabbreviatednameoftheindividualwhofirstassignedascientificnametotheplant inthiscaseHumphreyMarshall Theletter L intheLatinnameHederahelixL identifiesLinnaeusastheauthority Theauthoritynameisnottypicallyincludedinnurseryandlandscapeliterature Intheseedplants therearemanysystemsofplanttaxonomy likeA Engler J Hutchinson A Takhtajan A Cronquist ZhengWanjun etc MostcommonsystemsofplanttaxonomyareA Engler J Hutchinson在种子植物门中 有许多分类系统 象哈钦松分类系统 恩格勒分类系统 塔赫他间分类系统 克朗奎斯特系统 郑万钧系统等 目前最常用的是哈钦松分类系统和恩格勒分类系统 自然分类系统中两个主要系统的特点简介1 恩格勒 Enger 系统德国的恩格勒编写了两本巨著 植物自然分科志 和 植物分科志要 系统描述了全世界的植物 内容丰富并有插图 很多国家采用了这个系统 特点如下 在被子植物中 单性而无花被的为原始特征 所以将木麻黄科 杨柳科 桦木科等放在木兰科 毛茛科之前 认为单子叶植物比双子叶植物原始 1964年改变 把双子叶植物放在前边 便于同其他植物学家统一 目与科的范围较大 该系统较稳定而实用 所以在世界各国及中国北方多采用 如 中国树木分类 中国植物志 中国高等植物图鉴 等书均采用本系统 2哈钦松 J Hutchinson 系统英国的哈钦松在其著作 有花植物志科 中公布了这个系统 特点如下 认为单子叶植物比较进化 故排在双子叶植物之后 在双子叶植物中 将木本与草本分开 并认为乔木为原始性状 草本为进化性状 认为花的各部呈离生状态 花的各部呈螺旋状排列 具有多数离生雄蕊 两性花等性状均较原始 而花的各部分呈合生或附生 花部呈轮状排列 具有少数合生雄蕊 单性花等性状属于较进化的性状 哈钦松 J Hutchinson 系统 认为在具有萼片和花瓣的植物中 如果它的雄蕊和雌蕊在解剖上属于原始性状时 则比无萼片与花瓣的植物为原始 例如杨柳科等的无花被特征是属于退化的现象 单叶和叶呈互生排列现象属于原始性状 复叶或叶呈对生或轮生排列现象属于较进化的现象 目与科的范围较小 目前认为该系统较为合理 但原书中没有包括裸子植物 中国南方学者采用的多 如 南方植物园 广州植物志 园林树木1000种 树木学 海南植物志 等都是哈钦松分类系统 ThesystemofEnglerandPrantl hasservedlycommandeduniversalattention Theirsystemhasbeenwidelyaccepted thoughinrecentyearsithasbeensubjectedtosomecriticism ItisgenerallyadmittedthatmanyanomaliesintheolderarrangementswereadjustedandthatgreatcontributionsweremadetoourknowledgeofTaxonomicBotany Mr HutchinsonhasventuredtoexpresshisdissentfromEnglerandPrantl sviewsinthisbookandhasreturned wiselyasIthink tothepositionadoptedbytheauthorsoftheGeneraPlantarum sinceheregardstheRanalesontheonehandandtheMagnolialesontheotherasthestarting pointsofhisphylogeneticarrangement IdentificationistherecognitionofcharacteristicsoforganismsandtheapplicationofanametoanorganismwiththoseparticularcharactersThedichotomouskeyisthemethodemployedforidentifyingunknownorganisms Theevolutionofkeyshasbeentheresultofworkbytaxonomistswhostudythecharacteristicsoforganismsatsometaxonomiclevel category andoftendevelopkeysfortheiridentification Thisexerciseintroducesyoutotheconstructionanduseofadichotomouskey Itisnotmeanttoprovidestudentsamethodofquickmemorizationofscientificnames Theproficiencylevelofusingkeys andlearningnames isareflectionoftheamountoftimeonespendskeyingorganisms Themoretimespentusingkeys themorefamiliarthecharacteristicsoforganismsbecome andthemoreproficientonebecomeswithkeys 植物分类检索表定距检索表本检索表中 对某一种性状的描述是从书页左边一定距离处开始 而与其相对的性状描述亦是从书页左边同一距离处开始 其下一级的两个相对性状的描述又均在更大一些的距离上开始 如此逐渐下去 距书页左方愈来愈远 直至检索出所需要的名称为止 A1植物体无根 茎 叶的分化 低等植物门B1植物体不为藻类和菌类所组成的共生体C1植物体内有叶绿素或其它光合作用 藻类植物门C2植物体内无叶绿素或其它光合作用 菌类植物门B2植物体为藻类和菌类所组成的共生体 地衣植物门A2植物体有根 茎 叶的分化 高等植物B1植物体有茎 叶 而无真根 苔藓植物门B2植物体有茎 叶 也有真根C1不产生种子 用孢子繁殖 蕨类植物门C2产生种子 种子植物门 平行检索表 本检索表中每一相对性状的描写紧紧并列以便比较 在一种性状描述之后即列出所需的名称或数字 此数字重新列于较底的一行之首 与另一组相对性状平行排列 如此继续下去直至查处所需名称为止 1 花小 花冠辐射对称 含羞草亚科1 1 花大 花冠左右对称或略左右对称 222 花冠左右对称 并为蝶形花冠 蝶形花亚科3 2 花冠略左右对称 非蝶形花冠 苏木亚科 Artificialclassification2GrowthformWoodyplantsaregroupedintoarbor shrub vineandgroundcoveraccordingtotheirgrowthform thefourgroupsasfollow Arbor Anarbormaybedefinedasawoodyplantwhichatmaturity6 4 mormore withasingetrunk unbranchedforatleastseveralmeters Arborsarealsogroupedintolargearbor above31m bigarbor 21 30m middlearbor 11 20m andsmallarbor 6 10m accordingtotheirheight Theyarealsogroupedintoslow moderateandfasttreeaccordingtotheirgrowthrate Shrub Ashrubmaybedefinedasawoodyplantwithseveralperennialstemsthatmaybeerectormaylayclosetotheground Itwillusuallyhaveaheightlessthan6metersandnomorethanabout8cmindiameter Woodyvine Woodyvinesindicatethoseplantsthathaveperennialstemsthatcannotsupportthemselves Vinesuseotherplantsorobjectstoriseabovethegroundortheyliealongtheground Vinesattachthemselvestootherobjectswithtendrils 卷须 如葡萄等 orbytwining 茎缠绕 如紫藤 orsucker 吸附根 如凌霄等 ortendrilswithadhesivepads 吸盘 如爬山虎等 Thoughwoodyvineshaveperennialstems thesestemsrarelygetverylargeindiameter Creepingshrub Acreepingshrubcanbedefinedasawoodyplantwithseveralperennialstemsthosearecreepingform 如铺地柏 Shortcomingsofgrowthformclassification Thedistinctionbetweenarborsandshrubsisnotalwaysclear Weallknowthatalargecottonwood 三叶杨 isatreeandacreepingjuniperisashrub buttherearemanyshrub liketreesandtree likeshrubs 如木芙蓉在浙江一带是灌木 在这儿严冬枯萎 翌春又由根部萌发新枝 而在西南 成都老家又是乔木 辽东丁香在北京是灌木 在百花山海拔1000米以上是乔木 蓖麻在北方是草本 在西双版纳则是乔木 白兰花在苏 杭一带高仅1 2米 适于盆栽灌木 然而在云南 四川 广东 广西 福建等省 则高达数十米的乔木 3ClassificationofOrnamentalCharacteristicsTimbertrees foresttrees Thereisnobeautifulleaves flowersandfruits buttheyshowsomepromiseforlandscapeuse E g Gymnosperm 裸子植物 Catkinspecies 葇荑花序类 bamboo species竹类等 Ornamentalflowerplants beautiful colorful fragrantflowers E g 桂花 山茶 瑞香 牡丹 海棠等 Ornamentalfruitplants colorful uniqueshape sweetorpleasantflavorfruitsOrnamentalleafplants theplantleaveswithbeautifulcolorandshapeorfallcolortreesorspringcolortrees E g 鸡爪槭 柽柳 石楠 紫叶李等 Shadetrees thetreeswithawidespreadingcrownandgoodshade E g 桉树 樟树 鹅掌楸等 Vines Aweak stemmedplantthatderivesitssupportfromclimbing twining orcreepingalongasurface E g 紫藤 爬山虎 木香等 缺点 荫木类与林木类有重复 花木类与果木类有重复 4Classificationaccordingtotheusageoflandscapetreesinlandscapearea一 Specimentree风景树 孤赏树 公园树 Atreeofspecialinterestbecauseofitsshapeorflowerorfruitorfoliage placedinapositionofprominenceintheyardorpark 如南洋杉 日本金松 雪松 金钱松 龙柏 云杉 冷杉 紫杉 紫叶李 龙爪槐等 Thefiveworldfamousparktrees世界五大公园树种 雪松 金钱松 南洋杉 日本金松 巨杉 二 Treesforshade庭荫树 atreeplantedorvaluedchieflyforitsshadefromsunlighttreeinyardorpark atallperennialwoodyplanthavingamaintrunkandbranchesformingadistinctelevatedcrown includesbothgymnospermsandangiosperms一般多为叶大荫浓的落叶乔木 在冬季人们需要阳光时落叶 例如 梧桐 七叶树 槐 栾树 朴树 榉树 榕树 樟等 三 streettree treesforstreetplanting 行道树 Streettreesarelocatedinthepublicspacestripbetweenthecurbandsidewalk Theyservethedualpurposeofprovidingitsshadeforpeopleandvehicleandstreetlandscape 落叶或常绿乔木均可作行道树 但必须具有抗逆性强 耐修剪 主干直 分枝点高等特点 例如 悬铃木 槐 椴 七叶树 元宝枫 樟 银桦等 国外五大行道树属 银杏 悬铃木属 椴树属 七叶树属 鹅掌楸属 四 Ornamentalshrubs花灌木 indicateshrubsorsmallarborswithbeautifulflowersorcolorfulfruitplantedinurbanarea Therearemanyornamentalshrubswidelyplantedinurbanarea Theirornamentalvalueisprominence 例如 梅花 桃花 榆叶梅 连翘 丁香 月季等 五 Vines藤本类 具有细长茎蔓的木质藤本植物 它们可以攀缘或垂挂在各种支架上 有些可以直接吸附于垂直的墙壁上 他们不占或很少占用地面积 应用形式灵活多样 是各种棚架 凉廊 栅栏 围篱 墙面 拱门 灯柱 山石 枯树等的绿化好材料 对提高绿化质量 丰富园林景色 美化建筑立面等方面有独到之处 如 紫藤 凌霄 络石 爬山虎 常春藤 薜 bi 荔 葡萄 金银花 铁线莲 素馨 木香 炮仗花等 六 Formalhedgetrees绿篱树种 Hedgetreesgocloseplantinginrows usuallypruningthemasregularshape Theirusagesare 1 PrivacyandBoundaryDefinition Shrubsareusedtodefinetheboundarylinesofthepropertyandtoenclosetheprivategardenarea Suchplantingsmaybeclippedorfree growinghedgesorpossiblyinformalshrubborders wherewallsorfencesarenotappropriateordesired Theoutdoorlivingareaisanimportantpartofalandscapecomposition andprivacyisahighlydesirablefeatureofthisarea 2 ScreensandBackgrounds Liketreesandvines shrubsareusefulforscreeningundesirableviewsfromwithintheproperty Manyshrubsmaintaintheirbranchesandfoliagefromgroundupandthusprovideaneffectivescreen Frequently tallershrubs particularlyevergreens servethedualpurposeofprovidingabackgroundforsmallershrubs flowerbeds andgardenfeaturesandatthesametimeservingasascreen WalkandDrivewayAccent Shrubsareusedtoemphasizetheentrancetowalksanddrivewaysleadingtothehome Generally onlylow spreadinganddwarfformsareusedforthispurposebecausevisionshouldnotbeobstructed 用作绿篱的树种 一般都是耐修剪 多分枝和生长较慢的常绿树种 如 圆柏 侧柏 杜松 黄杨 大叶黄杨 女贞 珊瑚树等 也有以观赏其花果为主而不加修整的自然式绿篱 常用树种有 小檗 贴梗海棠 黄刺玫 珍珠梅 枸桔 木槿等 七 Groundcoverplants木本地被植物 Alow growingdensegrowthofwoodyplants plantedforornamentalpurposesortopreventsoilerosioninareaswhereturfisdifficulttogrow asindeepshadeor