Can plants absorb organic compounds?

Question

Plants are autotrophs, meaning that they grow by building organic matter out of inorganic compounds (and energy).

Is it then also true that plants are generally not capable of absorbing organic compounds? There are certainly some plants that can do it, e.g. carnivorous plants absorbing amino acids of their (dissolved) prey. But what about, say, the common sunflower on my balcony?

Answer 1

Yes plants can absorb organic compounds..For example plants can absorb citric acid

Due to citric acid’s ability to chelate metals and be absorbed by plants, it is hypothe-sized that exposure to it will increase the ability of wheat-grass to absorb macro- and micro-nutrients, as well as heavy metals, from soil.

Citric acid chelates absorption

Also plants have the ability to absorb and release sugars.

Plant roots are able to absorb sugars from the rhizosphere but also release sugars and other metabolites that are critical for growth and environmental signaling. Reabsorption of released sugar molecules could help reduce the loss of photosynthetically fixed carbon through the roots

Monosacharid absorption activity

I'm sure there are other examples, feel free to edit the answer.

Answer 2

There are whole groups of plants that don't photosynthesize, but which derive their nutrients from other plants in various ways.

For instance, the common (hereabouts) Snow Plant https://www.fs.fed.us/wildflowers/plant-of-the-week/sarcodes_sanguinea.shtml gets nutrition from soil fungi (mycorhizzae) which in turn get it from conifers.

There are a great many other parasitic plants, which derive some or all of their nutrients from other plants, or from soil fungi. See e.g. https://en.wikipedia.org/wiki/Parasitic_plant

Then there's the whole subject of mutualistic relationships between plants and mycorrhizae fungi: https://en.wikipedia.org/wiki/Mycorrhiza