Page 7 - 《广西植物》2020年第1期
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1 期                          丁炳扬等: 中国菱属 (菱科) 植物的分类研究                                         3

                                                         Field works were carried out in Eastꎬ Centralꎬ
   1  Morphological Characters                       Southꎬ Southwestꎬ North and Northeast Chinaꎬ and 41
                                                     populations from fifteen provinces were collected. The
       The diagnostic characters used to identify species  data used for variation analysis and principal component
   or infra ̄species of Trapa in China are as follows: horn  analysis (PCA) were mainly obtained from these popu ̄
   numbers of fruitsꎬ horn shape and positionꎬ fruit shape  lationsꎬ and its taxonomic implications were also evalua ̄
   and sizeꎬ shape and size of fruit crownsꎬ beak heightꎬ  ted (Jin & Dingꎬ 1995ꎻ Hu et al.ꎬ 2001ꎻ Wang et al.ꎬ
   bulge numberꎬ leaf shape and sizeꎬ indumentum (Li &  2006). Ten species from 33 populations were cultivatedꎬ
   Changꎬ 1977ꎻ Yanꎬ 1983ꎻ Wanꎬ 2000). Other charac ̄  and the developmental progressꎬ seedling morphologyꎬ
   tersꎬ such as annual floating herbsꎬ phyllotaxisꎬ flower  pollination experiments and morphological variation were
   solitaryꎬ 4 ̄merousꎬ ovary partly inferiorꎬ drupe etc.ꎬ  carefully observed (Ding et al.ꎬ 1996ꎬ 1999).
   show the stability among species and varieties and are  Hereinꎬ the principal diagnostic characters used to i ̄
   not used for identification.                      dentify species and varieties of Trapa are listed in the key.

                                   Key to the species and varieties

   1. Plants small and thinꎬ leaves less than 3 cm both in length and widthꎻ flowers pinkꎻ fruit bodies less than 1.2 cm
     high and less than 1.5 cm broad   1. Trapa incisa
   1. Plants stoutꎬ leaves often over 4 cm in length and widthꎻ flowers whitish or sometimes pink at beginning floweringꎻ
     fruit bodies more than 1.2 cm high and 1.5 cm broad    2
   2. Fruits(horns excluded) more than 1.5 cm × 2 cm × 1 cm (height × width × thickness)ꎻ crowns largerꎬ more than
     6 mm in diam.ꎻ flowers whiteꎻ native or cultivated   3
   2. Fruit (horns excluded) 1.2-1.5 cm × 1.5 -2 cm × 0.8-1 cmꎻ crowns smallerꎬ 3-5 mm in diam.ꎻ flowers white or
     sometimes pink at beginning floweringꎻ native   6
   3. Fruit beaks well ̄developedꎬ more than 3 mm highꎬ reflexed at apexꎻ fruits 4 ̄horned or 2 ̄horned   4
   3. Fruit beaks inconspicuousꎬ plane or sightly protuberantꎬ not reflexed at apexꎻ fruits 4 ̄hornedꎬ 2 ̄horned or 0 ̄
     horned       5
   4. Fruits 4 ̄hornedꎻ 2 lower horns (pseudohorns) sharp and barbellateꎬ or obtuse. 
            2a. Trapa natans var. natans
   4. Fruits 2 ̄hornedꎻ 2 lower horns degenerativeꎬ or bulged   2b. Trapa natans var. magnicorona
   5. Fruits 4 ̄hornedꎬ or without horns (degenerate to 4 ̄bulged)ꎬ slightly side ̄flatꎬ thichness vs width > 0.5 
           2c. Trapa natans var. komarovii
   5. Fruits 2 ̄hornedꎬ conspicuously side ̄flatꎬ thichness vs width < 0.5    2d. Trapa natans var. bispinosa
   6. Fruits conspicuously 4 ̄hornedꎻ 2 lower horns sharp or obtuse    2e. Trapa natans var. quadricaudata
   6. Fruits 2 ̄hornedꎻ lower horns degenerative to bulged   2f. Trapa natans var. complana


                                                         Herbs annualꎬ aquatic. Stem submergedꎬbranched
   2  Taxonomic Treatment                            or unbranchedꎬ internodes elongate. Leaves dimorphicꎻ
                                                     submerged leaves oppositeꎬ sessileꎬ simpleꎬ linearꎬ ca ̄
       Based on literature surveyꎬ field workꎬ specimen  ducousꎻ floating leaves alternate but aggregatedꎬ petio ̄
   examination and cultivation observationsꎬ taxonomic re ̄  lateꎻ leaf blades rhombic to reniformꎬ petioles inflated
   vision of Trapa from China were proposed and two spe ̄  at the middleꎻ stipules linearꎬ deciduous. Flowers
   ciesꎬ T. incisa and T. natans were recognized. For the  solitary in upper leaf axilsꎬ 4 ̄merous. Sepals 4ꎬ usually
   infra ̄species of T. natansꎬ another five varieties were  persistent as horns of fruit. Petals 4ꎬ white or pinkꎬ de ̄
   recognized as well.                               ciduous. Stamens 4ꎬ antesepalous. Ovary semi ̄inferior at
       Trapa L.ꎬ Sp. Pl. 1: 120. 1753. Type: T. natans L.  anthesisꎬ subsequently becoming inferior in fruit. Fruits
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