The following summary briefly describes how to use this key.
First time users should read through the illustrated help
files for an understanding of the methods used in this treatment as well as help
on how to measure or interpret each character.
- Use this key to
generate a list of grasses matching easily measured features.
- Do not guess.
When in doubt, leave it out!
- Start with 3 or
4 obvious features. Don't try to fill in all the boxes at the beginning.
You can return to this page and add more features as often as you need.
- For measurements,
an average of several specimens is best. For some measurements, you will need a
hand lens and a millimetre ruler.
- For definitions, see the glossary.
Interpretation and explanation of characters
- Measure height from the ground surface to the top of the plant along the stem.
- To measure the ligule, it is best to have a hand lens and millimetre ruler. At this point in
the key, you do not have to measure ligules less than 1 mm long. For ligules less than 1
mm, just enter 1. You can make finer distinctions, if necessary, further along in the key.
- Measure the leaf blades at the widest part of the leaf. Measure several and take
- The interpretation of spike here is not a botanical one. If it looks like a spike, and you
don't see any little branches at the base of the spikelets, choose spike. Several grasses do
not have true spikes, but to a non-botanist they do. These will be found in both categories.
Beware that the immature flowerhead of several grasses (such as Agrostis look like spikes.
Spread out the flowerhead to check for obvious branches. If they are there, it is not a spike.
- Measure the flowerhead length starting at the point where the first spikelet is attached to the
base (if a spike) or where the lowest branch (if branched) is attached, extending to the tip.
If it is a spike, measure from the base of the lowest spikelet.
Exclude the awns from the measurement.
- The spikelet is the flowering unit of the grass, comprised of two (rarely one or none)
glumes - small bracts at the base, and one or more florets. Florets are the reproductive
units of grasses consisting of the lemma, the palea and the enclosed reproductive components -
including the anthers which may be visible with a hand lens.
Measure carefully from the base of the spikelet to the tip, excluding awns if
there are any.
If the glumes are longer than the enclosed lemma (or lemmas), simply measure the glumes.
- Count the number of florets (the 'future seeds') in each spikelet. This can range from 1
to 20 or more. If your plant is mature and the seeds have begun to fall off, don't use
- Most grasses have two glumes (bracts) at the base of each spikelet, but some have only one, or even
none. Using a hand lens, look closely to see if the lower glume (also called the first glume) is shorter or
longer than the first floret.
- Awns are bristly or hairlike projections from the lemmas, and sometimes the glumes. Some
grasses don't have them - in which case, enter 0 in the box. If your grass has them, measure
them from where they project from the lemma.
- Where the awn attaches to the lemma is an important distinguishing characteristic. A hand
lens is helpful here. Answer 'along the back' if it attaches more than halfway down the back
of the lemma. Answer 'at or near the tip' if it seems to be coming from the tip, from between
two 'little teeth', or very near to the tip.