The Structure of Aristolochia tomentosa (Aristolochiaceae) Reproductive Organs

The dynamics of flowering and the structure of the flowers, gynaeceum, and androceum of the rare relict medicinal liana Aristolochia tomentosa Sims. were studied. The flower development from the stage of barely noticeable bud to opening was shown to last for 20 days, and each flower bloomed for five days. The flowers were protogynous. The pollen grains were oblate-spheroidal without apertures, with a polar diameter of 30.72 ± 1.89 μm, and an equatorial diameter of 33.21 ± 0.56 μm. The anatomical structure of the gynaeceum and androceum of A. tomentosa was found to be close to that of the Asian species A. manshuriensis. This similarity reflects the preservation of the features that were kept in the species after they deviated from their ancestral form.