Aspiring botanist and ecologist with a passion for science communication. The door to learning about the natural world is always open; let’s go outside and play

Feb 8, 2016

Pebble Plants

Lithops

these little ground nubs grow all across Nambia, South Africa, Botswana, and perhaps also Angola
they’re colloquially referred to as pebble plants
or living stones
it’s not hard to guess why
they’re bulbous succulents that grow close to the ground and have a rough textured upper leaf surface
they’re composed of two leaves joined together
and they have hardly any stem at all
the textured tops of each leaf is actually clear
these clear panels are called leaf windows and they allow sunlight to enter the interior of the modified leaf so photosynthesis can occur
why do they need these patches?

well
most of pebble plants grows under ground
the leaves you see are only part of the puzzle
living stones tend to live in hot, dry, desert-like areas
so by growing mostly underground
they are able to expand their surface area available to absorbing ground water and soil nutrients
and they minimize their exposure to excess heat from the sun
living underground is great
but what’s not so great about it is that there’s not a whole lot of sunlight down there
that’s why Lithops have leaf windows
these windows allow the plants to obtain the amount of solar energy necessary for photosynthesis

*Can you spot the Lithops? (Photo by Joel Ignacio)*

so their rock like appearance is beneficial in two ways
for the sake of photosynthesis and for growing in desert conditions
impressively enough
there’s another reason why Lithops masquerade as rocks
you may have guessed it
but they look like this so as to avoid being eaten by herbivores
not too many herbivores go grazing for small rocks
so the Lithops are safe
their leaves are not green
rather they come in shades of cream, grey, and brown to further the charade

but
they do break this monochromatic color scheme every once in a while
throughout the winter months
a new pair of leaves grows within the existing ones
and
come spring
the new leaves emerge and the old shrivel up and dry out
around the time of the summer solstice
sweetly scented yellow or white flowers pop out from between the new leaves

What a strange planet we live on. It’s hard to believe that selective pressures could be all it takes to change plants into rocks. Just another day to appreciate the majesty of the Earth.