Ultrahydrophobicity '': an example of the
lotus effect after rain The
leaves of
Nelumbo are highly water-repellent (i.e. they exhibit
ultrahydrophobicity) and have given the name to what is called the
lotus effect. Ultrahydrophobicity involves two criteria: a very high water contact angle between the droplet of water and the leaf surface, and a very low roll-off angle. This means that the water must contact the leaf surface at exactly one, minuscule point, and any manipulation of the leaf by changing its angle will result in the water droplet rolling off of the leaf. This helps reduce the area of contact between the water droplet and the leaf.
Thermoregulation An uncommon property of the genus
Nelumbo is that it can
generate heat, which it does by using the alternative oxidase pathway (AOX). This pathway involves a different, alternative exchange of
electrons from the usual pathway that electrons follow when generating energy in
mitochondria. The typical pathway in plant mitochondria involves
cytochrome complexes. The pathway used to generate heat in
Nelumbo involves
cyanide-resistant alternative oxidase, which is a different electron acceptor than the usual cytochrome complexes. The plant also reduces
ubiquitin concentrations while in
thermogenesis, which allows the AOX in the plant to function without degradation. Thermogenesis is restricted to the
receptacle,
stamen, and
petals of the flower, but each of these parts produce heat independently without relying on the heat production in other parts of the flower. There are several theories about the function of thermogenesis, especially in an aquatic genus such as
Nelumbo. The most common theory posits that thermogenesis in flowers attracts
pollinators, for a variety of reasons. Heated flowers may attract insect pollinators. As the pollinators warm themselves while resting inside the flower, they deposit and pick up
pollen onto and from the flower. Others theorize that heat production facilitates the release of
volatile compounds into the air to attract pollinators flying over water, or that the heat is recognizable in the dark by thermo-sensitive pollinators. None have been conclusively proven to be more plausible than the others. After
anthesis, the receptacle of the lotus transitions from a primarily thermogenic to a
photosynthetic structure, as seen in the rapid and dramatic increase in
photosystems, photosynthetically involved pigments, electron transport rates, and the presence of
13C in the receptacle and petals, all of which assist in increasing photosynthesis rates. After this transition, all thermogenesis in the flower is lost. Pollinators do not need to be attracted once the
ovary is fertilized, and thus the receptacle's resources are better used when it is photosynthesizing to produce
carbohydrates that can increase plant biomass or fruit mass. Also, the
elephant yam, which heats its flowers to attract pollinators. In addition, the
carrion flower, which heats itself to disperse water vapor through the air, carrying its scent further, thus attracting more pollinators. '' bud
Similar species The leaves of
Nelumbo can be distinguished from those of genera in the family
Nymphaeaceae as they are
peltate, that is they have fully circular leaves.
Nymphaea, on the other hand, has a single characteristic notch from the edge in to the center of the lily pad. The
seedpod of
Nelumbo is very distinctive. == Taxonomy ==