BOTANY. 43 



to 45° west longitude from Greenwicli, and extends over 40,000 square 

 miles. 



2. Maritime, or Saline Plants. These are plants which grow on the 

 border of the sea, or of salt lakes, and require salt for nourishment, as 

 Salicornia, glasswort, Salsola, saltwort, Anabasis. Such plants are often 

 called Halophytes. Under this head may be included littoral and shore 

 plants, such as Armeria, sea-pink, Glaux, and Saniolus. 



3. Aquatic Plants, growing in fresh water, either stagnant or running, 

 as Sagittaria, arrowhead, Nympltma, water-lily, Potamogetoji, pond-weed, 

 Suhularia. awlwort, Utricularia, bladderwort, Stratiotes, water-soldier, 

 Lemna, duck-weed, Pistia, Conferva, Oscillatoi'ia;, and Ranunculns 



fluviatilis. Some of these root in the soil, and appear above the surface 

 of the Avater ; others root in Ihe soil, and remain submerged ; while a few 

 swim freely on the surface without rooting below. 



3. Afnphibious Plants, living in ground which is generally submerged, but 

 occasionally dry, as Ranunculus aquatUis and sceleratus, Polygonum 

 ainphibum, Nasturtium ampJiibium. The form of the plants varies accord- 

 ing to the degree of moisture. Some of these, as Limosella aquatica, grow 

 in places which are inundated at certain periods of the year ; others, such as 

 Rhizophoras, mangroves, and Avicennias, form forests at the mouths of 

 muddy rivers in tropical countries. 



B. Land Plants which Root in the Earth and Grow in the 



Atmosphere. 



Sand Plants : as Care.v arenaria, Ammopliila arenaria, Elymus 

 arenarius, and Calamagrostis arenaria, Avhich tend to fix the lose sand. 

 Plantago arenaria, Herniaria glabra, Seduni acre. 



6. Chalk Plants ; plants growing in calcareous soils, as some species of 

 Ophrys, Orchis, and Cypripedium. 



7. Meadow and Pasture Plants ; as some species of Lotus, bird's foot 

 trefoil, a great number of grasses and trefoils, the daisy, dandelion, and 

 buttercups. 



8. Plants Pound in Cidtivated Ground. In this division are included 

 many plants which have been introduced by man along with grain, as 

 Centaurea cyanus, corn blue-bottle. Sinapis arvensis, common wild 

 mustard, Agrostemnia, corncockle, several species of Veronica and Eu- 

 phorbia, Lolium. temulentum. Convolvulus arvensis, Cichorium intybiis ; 

 also plants growing in falloAV ground, as Rmnex acetosella, Carduus nutans, 

 Echium vulgare, Artemisia campestris, and Androsace septentrionalis. In 

 this division garden weeds are included ; such as Groundsel, Chickweed, 

 Lamium amplexicaule, Chenopodiu?n vulgare and viridc. 



9. Rock or Wall Plants ; Saxifrages, Wall-flower, Linaria cy?nbalaria, 

 Draba miiralis, species of Sisymbrium and Sedum, Aspleniiwi, Rata mura- 

 ria, and some lichens and mosses. 



10. Plants Found on Rubbish Heaps, especially connected with old 



43 



