mini-lecture of the day: Inga

Inga is a genus of trees that are quite common in the neotropics. Two of the species I worked with last summer were Inga (thibaudiana and pezizifera) so I’ve gotten fairly good at identifying the genus.

I find Inga really interesting because of its extrafloral nectaries. “Extrafloral nectaries” may sound really complicated, but actually they’re fairly simple: “extra-floral” meaning not on flowers, and “nectaries” meaning something that provides nectar. With inga, the nectaries are on the leaves, and they attract ants that help protect the tree from herbivory and vines.

an ant drinking out of a nectary on an inga leaf
an ant drinking out of a nectary on an inga leaf

Another interesting thing about inga is that it has compound leaves. This means that all the parts that look like leaves are actually leaflets, and the leaves themselves are made up of four to twenty leaflets. Inga leaflets always come in pairs. Inga leaves (and leaflets) can be fairly small, or really big.

inga
inga
not an inga: ends with a single leaflet
not an inga: ends with a single leaflet
sometimes Inga leaves are really big! This picture has one leaf with eight leaflets
sometimes Inga leaves are really big! This picture has one leaf with eight leaflets

Lastly, some Inga can have a winged rachis. The rachis is the part of the leaf that connects all the leaflets together, and when it has a lot of leaf-tissue on it, it’s considered winged. I don’t know if this serves any biological purpose, but it makes them look really cool.

that bug is standing over the rachis, which is winged in this picture
the bug is standing over the rachis (winged in this picture)
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s