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The general intent of these keys is to enable you to identify asters and goldenrods in the field with only a hand lens.  Those who do not have access to laboratory equipment, such as microscopes, should not have to collect specimens, especially specimens of rare species.  However, given the large number of aster and goldenrod species, and the subtle distinctions between them, this subject can get quite complicated.  So if you do not collect specimens or take good photographs, you should take detailed notes on what you saw in the field.

In creating the logic of the keys I have tried to use "strong characteristics" whenever possible; that is, those that are readily identifiable and present (or not) for all or nearly all members of a given species or group of species.  For example, "strongly and conspicuously clasping leaves", and "densely glandular phyllaries", are two strong characteristics.  On the other hand, stem height tends to be too variable and sensitive to environmental conditions to be used in the logic of keys (though it may be stated in detailed descriptions).

Botanists use a number of subtle but meaningful terms to describe the extent to which given species exhibit particular traits.  When no adjective qualifies a particular trait, one may assume that the species either always or never exhibits that trait.  When the terms "typically", "mostly" or "commonly" are used, one can assume that the trait or character occurs nearly always in a particular species.  For example, "the leaves are typically glandular".  Conversely, when the terms "rarely", "scarcely" or "seldom" are applied, one may assume that the trait or character hardly ever occurs.  For example,  "Rays are mostly blue-violet, rarely white".

Yet other adjectives are used to qualify the frequency of occurrence even more, such as "often", "occasionally", "frequently" or "infrequently".  These adjectives describe a less certain set of conditions that provide a lesser degree of confidence.  So for example, the statement:  "Stems are occasionally stout." implies that the stems may equally often not be stout.

So, one needs the read keys carefully and note the subtle distinctions that are being made.  If I state, for example, that the flower heads are often nodding in bud, don't be surprised to find specimens which are not nodding in bud.

Notes on the aster keys:

The keys to the asters start with the familiar dichotomy determined by whether the basal and lower stem leaves are both cordate and petiolate.  This is a useful way to start the keys, for it is fairly easy to determine whether a leaf is cordate or not.  Additionally, basal and lower stem leaves may be the only plant parts present early in the season.

The second dichotomy in the keys to the asters is based on whether the capitulescence is in the shape of a  panicle or not.  This trait is also visible throughout much of the growing season, even though flowers or buds may not yet be present.  If one can identify a developing panicle, it may be possible to continue at least part way through the key, and eliminate some possibilities.

It was decided to describe the paniculiform species earlier in the key.  This is because the corymbiform capitulescences of some of the species are not always well-formed, and thus it may sometimes be difficult to determine whether a particular plant has one type of capitulescence or another.  This is particularly the case for some of the Eurybias and Oclemenas, which often don't have many "flower heads" and form what's called "lax" corymbs.  With the 2010 version of the asters key, you will find that the term "corymb" has been eliminated altogether.  I don't think it applies ideally to many of the asters.  In other words, in the 2010 asters key, a plant either has a panicle or not.

Note on the Goldenrods Key

The obverse is the case with goldenrods.  The term "panicle" seems too imprecise to describe the variation in capitulescences of many of the goldenrods.  So that term has been dropped from the 2010 goldenrods key.  In other words, in the 2010 goldenrods key, a plant either has a corymb or not.
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