Most of the time they reproduce asexually by producing gemmae. "Tetraphis pellucida" reproduces asexually through the use of asexual propagules called gemmae. Pygmy sundews reproduce asexually using specialized scale-like leaves called gemmae. This species reproduces asexually by gemmae that are produced within gemmae cups. The gemma cups are cup-like structures containing gemmae. Short vegetative stems may end in a stalk-bearing clusters of gemmae. Some plants have specialized structures for reproduction via fragmentation, such as "gemmae" in liverworts. It is unknown whether the leafy stage can produce such gemmae. Mutilation leads to a permanent change in lifetime trajectory, because workers lacking gemmae never mate. The gemmae are found either in gemma cups or stalks. The discus-shaped gemmae are readily dislodged from the cups by splashes of rainwater. Some botanists believe that the gemmae might be adaptations to a dry climate and fires. The gemmae are bilaterally symmetrical and are not differentiated into dorsal and ventral surfaces. In "Metzgeria", gemmae grow at thallus margins.