| populus, absent, species, present, usually, phloem, sucrose, sometimes, leaves, catkin, initially, d ahlgren, aperturate, persistent, genera, chosenia, gynoecium, entire, several, lamina, descriptions, mostly, leaves, without, stamens, family, willow, crystals, mirbel, plants, filaments, cyanidin, ha ving, anther, oligosaccharides, unbranched, development, salicaceae, families, commonly, anatomy, co herent, purpurea, epidermis, isobilateral, recorded, mesophyll, floral, generally, cronquist, supero rder |