Lampenflora, also known in English as lamp-flora or lamp flora are autotrophic lifeforms present in natural or artificial caves associated with permanently installed lighting. Lampenflora are a problem with respect to the conservation of cave features, artworks, and fauna, and consequently their presence in caves can be referred to by the terms green sickness and la maladie verte.

The term "lampenflora" has come to English from German. It was coined by botanist Klaus Dobat in the 1960s, and just means "lamp flora" or "flora of the lamps"

So far the following types of lampenflora have been described:

Fungi and roots growing into caves, as well as plants growing in naturally illuminated areas, are not lampenflora.

The requirements for the development of lampenflora are sufficient (artificial) light and moisture. An increase in nutrient content (e.g. fertilizer usage on land above the cave) or heat (e.g. incandescent lighting) may lead to an increase in lampenflora. The germs, seeds or spores can get brought into the cave by air, water, animals or people.

Lampenflora tend to grow best on rough surfaces and in red or blue light due to the plant's absorption rate of this light into its chlorophyll. However, pre-established colonies of lampenflora can survive even after long periods of light deprivation.

In the aphotic (lightless) part of caves, short-term growth of photosynthetic plants is possible thanks to the seed's nutritive tissue. After this is consumed, the plant dies.^{[citation needed]}

Lampenflora can cause various problems: Since lampenflora changes the appearance of show caves, it can give visitors wrong impressions of natural caves. It does not exist in caves not developed for humans. The weak acids excreted by lampenflora can also cause damage to and change limestone and other rocks. Lampenflora is especially dangerous to artifacts present in caves, such as cave paintings. The appearance of algae was one of the reasons the Lascaux cave was closed to the public.