6) Morphological characteristics of sweetpotatoes

[Stems]	Stems tend to be creeping. Longer ones can reach up to 5 m or more in length. However, upright-type (grassy) stems with short intervals between nodes do not creep. Within a stem, adventitious roots come out at each node.
[Leaves]	Leaves come in a range of shapes including round, heart- and shield-shaped. The depths of leaf notch and leaf size are also diverse. Widths from 7 to 15 cm are seen, with petioles ranging from 7 to 30 cm.
[Roots]	Roots are adventitious, and are generated from tubers, stems, and the base of the petiole. Some roots generated from nodes swell to become tubers, but most such roots remain very thin or take on a slightly swollen, pencil-like appearance.
[Flowers]	Sweetpotatoes bloom well and bear fruit in tropical and subtropical regions; in Japan, however, they bear no fruit because of the presence of cold weather and frost, though they can bloom occasionally in early autumn.
[Seeds]	Seeds resemble those of morning glories. They are hard, and do not germinate unless cut open or treated with concentrated sulfuric acid at the time of sowing. When immersed in water for about 24 hours after treatment, seeds will produce 3-4 heart-shaped leaves about 3 weeks after sowing, in a warm bed of about 30°C.