Page:Popular Science Monthly Volume 50.djvu/693

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sure that the models are absolutely true to the subjects furnished for them, wherever they were grown.

It is interesting to make a study of several species of a single order, noting at the same time the typical characteristics and the variations of detail. Take, for instance, one of the most common and easily recognized orders—that of the Malvaceœ. Here we have no less than eight species, representing six genera. They are: Hibiscus clypeatus, Hibiscus palustris, Spheralcea acerifolia, Sida carpinifolia, Sida napœa, Nuttallia malvœflora, Anoda Dilleniana, and Malva miniata.

All these species show the distinguishing characteristics of the family—the translucent texture of the petals, with their clearly marked veinings; the delicate tints of the corolla, varying from white to deep rose-purple, or, as in the case of the Sidas, to a tawny, crimson-throated orange. All have certain enlarged details in which we again easily recognize the distinguishing features of the order the column of stamens, the peculiarly shaped anther (in the example of Hibiscus palustris shown in two stages of its development, while an immature anther of H. moscheutos is given), the style with its capitate stigmas, and also both longitudinal and cross sections of the ovary showing the arrangement of the ovules in their cells.

In Spheralcea acerifolia the inflated, heart-shaped anther is speckled with pale red like a bird's egg, and here we have also a pollen grain magnified one thousand times. Among the details of the Nuttallia is a sepal with its stellate hairs and a single one of these hairs enlarged two hundredfold and looking like a tiny snow crystal. Probably none of the models illustrate better the value of these magnified details, in studying the more recondite orders, than those of the Euphorbiaceœ, where the inflorescence owes its beauty to a highly colored involucre, while the flower proper is reduced to a single organ. So in Jatropha officinalis the brilliant, flame-colored involucre attracts the eye, while the insignificant flower is represented by a solitary stamen or pistil. The three-celled ovary, the three styles each with its two-cleft stigma, may here be carefully studied without recourse to the aid of the lens. Especially delicate is the little Euphorbia montana, gray as if with the dust of the California deserts it comes from. A detail of the inflorescence shows the inner side of the involucral bract to which the sterile flowers or stamens are attached.

Still another plant of the same order is most baffling to the student, from the arrangement of the pale pink flowers on the margins of what appear to be flat, cactuslike leaves, but which are in reality the rudimentary branches of this curious growth; this is the Xylophylla Roezlii.