Bartholina burmanniana leaf

The stem of Bartholina burmanniana emerges from the base of its single, prostrate leaf. The leaf shape is nearly round, the heart-shaped basal lobes in picture can be seen to fold around the stem and overlap, almost completing the circle. The reddish, erect stem has a covering of soft, long hairs. Leaf hairs are conspicuous along the margin.

The two-species genus of Bartholina resembles the larger Holothrix genus. Holothrix and Bartholina plants have strange, underground structures, knuckle- or carbuncle-like growths on the stem base above their tubers.

These things, possibly stubby roots (as the plants lack “ordinary” roots), may perform root functions of absorbing nutrients and water. That is if the tuber walls themselves are impermeable, which is yet unknown (Liltved and Johnson, 2012).