Nature and development of plants . des the loosestrife (Lysimachia and Stciro-nema), star flower (Triciitalis), shooting star (Dodecatheon)and cultivated forms of the cyclamen and primroses. Proceeding to the gentian order (Gentianales), it will benoted that the flowers are variable and not as clearly character-ized, the corolla being sometimes wanting or polvpetalous. Thereduction of the stamens to a single whorl and the pistils usuallyto two in number indicate points of advance that are to beassociated with the twisting of the petals in the bud and theopposite arrangement of the leaves as di
Nature and development of plants . des the loosestrife (Lysimachia and Stciro-nema), star flower (Triciitalis), shooting star (Dodecatheon)and cultivated forms of the cyclamen and primroses. Proceeding to the gentian order (Gentianales), it will benoted that the flowers are variable and not as clearly character-ized, the corolla being sometimes wanting or polvpetalous. Thereduction of the stamens to a single whorl and the pistils usuallyto two in number indicate points of advance that are to beassociated with the twisting of the petals in the bud and theopposite arrangement of the leaves as distinguishing featuresof the order (Fig. 328, B-D). Note should be made of the fact DEVELOPMENT OF PLANTS 441 that the two pistils often do not cohere, doubtless a survival ofa more primitive condition. The Gentianales include the ash (Frax-inits), lilac (Syringa), Forsythia, olive (Olea), valued for fruitand oil, fringe tree (Chionanthus), privet (Ligustrum), jasmine,Strychnos, yielding the alkaloid strychnine, oleander (Xeriitm),. Fig. 328. Primulales and Gentianales: A, flower of loosestrife (Stciro-ncma). Above flower in section, showing cohesion of single row of sta-mens to base of corolla and the numerous ovules on a* free central pla-centa. These are the most important characteristics of the order. B,fringed gentian (Goitiaiia), showing leaf arrangement and twisting ofpetals in bud, b, characteristics of the order. C, section of flower. D,fruit, the two carpels separated. the gentians, marsh pink (Sabbatia), the aquatic floating heart(Liiiniaiithciiutiii) and the highly specialized plants of the dog-bane and milkweed families. The latter family is distinguishedby the microspores being united into club-shaped pollinia that 442 THE POLEMONIALES arc attached, one from each of the two adjoining anthers, to apeculiar hook, so that the leg of the insect becomes caught inthe hook and withdraws the pollinia in pairs. 152. Polemoniales, or Phlox Order.—This group is the richesti
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