Asters and Goldenrods Primer
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|It is useful to examine various characteristics of plant stems when trying to identify a species. We will look at examples of each of the following characteristics: stem thickness, surface features, straightness and height. These features tend to be consistent for individuals of a given species, though there may be some variability in some features due to environmental conditions, such as amount of available moisture or sunlight, or the extent of competition. Height and thickness are often affected by environmental conditions, whereas surface characteristics and straightness are not.|
Individuals of a given species tend to have stems of more or less the same thickness. Stems tend to be thickest at the base of a plant, and thinner toward the top, though in some cases the differences are minimal. Stems are either thin or stout. "Stout" would be applied mostly to plants that are relatively tall and large. A species that is typically short may have stems that are thick in proportion to the height of the plant, while stems of that same diameter would not be considered thick for a different species which is typically much taller.
This is a good opportunity to
introduce two technical terms that occur frequently in field manuals and
textbooks: proximal and distal. Proximal means
"near" or "in the proximity of". Distal means
"far away" or "distant". Please refer to the glossary
entry for these terms for additional details and an example.
|Stems of Eurybia divaricata (left) are considered "thin", whereas stems of Solidago squarrosa (right) are considered "thick" and "stout". (This trait is difficult to portray photographically.)|
Stem Surface Characteristics
many technical terms used to describe surface characteristics.
These same terms are applied to leaf, branch, peduncle, bract, phyllary
and seeds as well. Please refer to the Glossary
for images and examples. (Or, click links below.) We mention the most
commonly used terms here.
Smooth. Lacking hairs. (No hairs!!)
As a general rule, hairiness increases
from the proximal
end to the distal
end of a stem or branch. Stems that are glabrous proximally, often
become glabrate or pubescent distally. Stems that are glabrate
proximally, will usually be more-densely pubescent distally. Stems
that are pubescent proximally, will almost certainly be pubescent
distally as well. In know of no exceptions to this. There
are very few asters or goldenrods that are totally glabrous. Those
that are mostly glabrous have a minimal amount of pubescence distally,
even if only on peduncles or near branch leaf axils.
|Stems are variously straight or flexuous (bent at the nodes). "Flexuous", does not mean that a stem curves when it gets longer, or because it was bent around some obstacle, or due to the wind. It means, strictly "bent at the nodes" (where leaves or branches attach to the stem). Shown below: Solidago flexicaulis (left) and Solidago ulmifolia (right).|
In many cases, this characteristic is not
exhibited at the proximal end of a stem. That is, the stem becomes
flexuous only distally or above, as where the flowering branches
occur. In other cases, stems are flexuous throughout.
This trait is heavily influenced by
"environmental" factors, such as availability of moisture or
sunlight, or the extent of competition. Nevertheless, some species
attain a height of only 2 to 3 feet, whereas others may reach 5 or 6
feet in stature. For example, Solidago juncea and Solidago
nemoralis possess some similarities. They both may have basal
and lower stem leaves during flowering, and they both may have tufts of
small leaflets in axils
of larger leaves or branches. One should use caution when in dry
locations, for a depauperate
S. juncea could be confused with a normal-height S. nemoralis.
Check other characteristics, such as stem hairiness or leaf color to
All photographic images and descriptions in
this guide are the copyright of Arieh Tal, 2008-2009. All rights reserved. You
may print an archival copy of these pages for your own use, as for
example, to use when conducting field observations. However, you may not
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permission from the author/ photographer. Please respect copyrights.