The Unmitigated Gall!

On my hike up Kennedy Ridge this morning  the most colorful thing I saw by a longshot:

Oak gall

Oak gall

Some folks call them oak apples.  Us science types call them galls.  What is a gall and why do they look so tasty.

A gall is an abnormal growth which can be found on almost any part of a plant, though the leaves are especially popular.  The are generally the work of immature insects, though galls can also be caused by fungi or even other plants (like mistletoe).

Erineum gall on a maple leaf

Erineum gall on a maple leaf

They are basically “plant tumors”, though unlike human tumors they generally do not harm the host plant, just make it a little ugly temporarily.

Midge's gall on a hairy ceanothus

Midge’s gall on a hairy ceanothus

There are over 1500 species of gall producers though around here the most common are midges, aphids and wasps.

Gall wasp

Gall wasp

Basically these species create the gall for the purposes of food or shelter for themselves or for their young.  Galls can vary in shape and size from a simple wart on a manzanita leaf to a gnarly spiked ball on a ceanothus to the cue ball sized oak gall.

Willw gall

Willw gall

Each species is very picky about what plant they start their galls on.  In our area the most popular hosts are oaks, willows, ceanothus and members of the aster family.

Gall fly's handiwork on a goldenrod

Gall fly’s handiwork on a goldenrod

Interestingly, some galls are useful to human culture. The Cynips gallae-tinctoriae has been used as a source of ink. These galls contain 50 to 65 percent tannic acid and are very useful as ink or in dyes for wool. The Greeks used the Cynips theophrastea gall for lamp fuel. Honeydew producing galls are used to attract bees and flies in the agricultural industry. Some galls have been known to be used for food and medicine.

Gall midge

Gall midge

And if you can’t get enough gall there’s even a book devoted to it:

Thanks for reading everyone, have a great weekend.

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4 Responses to The Unmitigated Gall!

  1. ocdreader says:

    Those oak galls look super tasty 🙂

  2. Cope says:

    Rambler, very timely post. Last Saturday i was leading a forest walk on fall leaf color (out here on the east coast) and someone in the group handed me the dried up leaf of a Black Oak (Quercus velutina (I would have italicized this if I knew how). She pointed to several little spherical bumps and asked, “What are these?”. They were actually little galls, sorry, I can’t tell you what species was the culprit. If you can remember what an eastern deciduous forest looks like around this time of year, peak color hit the Bronx a week ago today. It was spectacular!

  3. john pavelko says:

    Ron…how about gall bladders???I think I have an infection caused by a wasp. What is the remedy? My “friends” are advising me to drink large quantities of gin??? jp

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