. Lessons with plants. Suggestions for seeing and interpreting some of the common forms of vegetation. the middle; spatulate, whichis oblong with the lower end narrow; oval, whichis broadly elliptical; orbicular, circular in outline;deltoid, or triangular; cuneate, or wedge-shaped; linear, or several times longerthan broad, and the same widththroughout; needle-shaped, as inpines and spruces. If any ofthe type forms are reversed,or inverted, the fact is ex-pressed by the prefix oh; asoblanceolate, obovate. Combi-nations of these terms, togetherwith the use of familiar adjec-tives (as short-ovat
. Lessons with plants. Suggestions for seeing and interpreting some of the common forms of vegetation. the middle; spatulate, whichis oblong with the lower end narrow; oval, whichis broadly elliptical; orbicular, circular in outline;deltoid, or triangular; cuneate, or wedge-shaped; linear, or several times longerthan broad, and the same widththroughout; needle-shaped, as inpines and spruces. If any ofthe type forms are reversed,or inverted, the fact is ex-pressed by the prefix oh; asoblanceolate, obovate. Combi-nations of these terms, togetherwith the use of familiar adjec-tives (as short-ovate, long-lan-ceolate, round-obovate, etc.). Cordate-ovate crenate leaf expreSS mOSt of the COmmOUof catnip. outlmes ot leaves. 132. Aside from the general outline, the formof the leaf is determined by the shape of itsapex and base. The apex may be acute or end-ing in a sharp angle (Figs. 108, 114); acuminate,ending in a long point (Figs, 82, 115); obtuse, orblunt (Fig. 98); truncate, or squared (S, Fig. 59);retuse, or indented (as in the upper leaves inFig. 106). The base may be cordate, or heart-. FiQ. 116. THE FOBMS OF LEAVES 119 shaped (as in Fig. 116, which is a cordate-ovateleaf); rentform, or kidney-shaped; anriculate, oreared; sagittate, or arrow-shaped; abrupt, or sud-denly narrowed to the petiole (as in the broaderleaves in Fig. 114); gradually narrowed (as inFigs. 97, 99). The cavity or recess in the baseof a leaf, like the grape or moonseed, (Figs. 80,81, 111) is a sinus. 133. The features of the margins of leaves,like their forms, are interesting because they areintimately related to the origin or • evolution of theparticular leaf (and, therefore, of the plant), andalso as a means of affording descriptive char-acters. The simple straight margin is said to beentire (Figs. 85, 102, 113, 114). Departures fromthis form are the serrate, or saw-toothed (Fig. 91);dentate, or toothed (Figs. 79, 80, 115, the lastbeing, perhaps, intermediate between serrate anddentate); cren
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Keywords: ., bookauthorbai, bookcentury1900, bookdecade1900, booksubjectbotany
