ID Tool Filter Guide


At leaf vein angles - galls located exclusively in the inside of the intersection between the lateral veins and main veins of the leaf.
Between leaf veins - galls are not specifically located only on leaf veins. Galls with this term may sometimes incidentally appear close to veins.
Bud - galls are located in buds (often found where branches intersect the stem, can be mistaken for stem galls).
Flower - galls are located in flowers. Note this is a botanical term referring to reproductive structures, and some flowers (eg oak catkins) may not be obviously recognizable as such.
Fruit - galls are located in fruit. This is a botanical term referring to seed-bearing structures, and some fruit (eg maple samaras) may not be obviously recognizable as such.
Leaf midrib - galls are located exclusively on the thickest, central vein of the leaf.
Lower leaf - galls are located on the lower (abaxial) side of the leaf.
On leaf veins - galls are located exclusively on or very close to the veins of the leaf, including but not limited to the midrib.
Petiole - galls are located on the part of the midrib between the leaf and the stem.
Root - galls are located on the roots of the plant or near the base of the stem.
Stem - galls are located anywhere in or on the stem (except within buds, which are occasionally deformed by gall inducers enough to appear as stem galls).
Upper leaf - galls are located on the upper (adaxial) side of the leaf.
Leaf edge - galls are exclusively located around the edge of the leaf, often curled or folded.
Yes - the gall could be removed from the plant without destroying the tissue it’s attached to (detachable).
No - the gall could only be removed from the plant by destroying the tissue it’s attached to (integral).
NOTE: Galls that have detachable parts but leave some galled tissue behind (more than a scar or blister), are only detachable in some parts of the season, or may be detachable or not, are included in both terms.
Hairy - the gall has some hairs, whether that's only a sparse pubescence of short hairs or a dense coat of long wool that obscures the gall or stiff bristles (as in Acraspis erinacei).
Hairless - the gall has no visible hairs at all. Note that late in hte season, hairs may wear off some galls.
Erineum - the distinctive "sugary" crystalline texture formed by many eriophyid mites.
Sticky - the gall exudes some kind of sticky fluid. In some cases this fluid is attractive to ants and is often visible as a wet sheen in photos, but ideally it should be tested by touch in the field.
Leaning - the gall is at an angle from the surface it is attached to.
Erect - the gall stands at nearly 90 degrees from the surface it is attached to. Includes the majority of detachable galls.
Integral - the gall is integral with the surface it is attached to. It may not be flat, but it doesn't protrude out from the surface leaving an angled gap. Includes nearly all non-detachable galls.
Supine - the gall is only attached at its base but lays nearly flat along the surface it is attached to for most of its length.
Thin - when the gall is cut open, it reveals an interior matching the shape of the exterior. The walls are not thick enough to conceal the shape of the chamber within.
Thick - when the gall is cut open, the interior is full of tissue except for the small chamber containing the larvae. The walls are thick enough that the shape of this chamber could (but may not necessarily) differ from the shape of the exterior.
False chamber - when the gall is cut open, there are two chambers, only one of which contains larvae.
Single - the gall's structure is built to accomodate only a single space for a gall-inducer larva, pupa, or adult.
Multiple - the gall's structure is built to accomodate spaces for multiple gall-inducer larvae, pupae, or adults.
NOTE: If multiple larvae are found in one space, these may be inquilines rather than gall-inducers.