Effect of Artificial Keys

Targets in most keys follow the taxonomic hierarchy, so are one rank lower than the rank of the key. For artificial keys, however, targets can be anywhere in the taxonomic hierarchy. This section shows several examples of these keys from FNA and FPNW using diagrams that extend the types of diagrams used so far. In particular, diagrams in this section use a dashed line

to show when the keying hierarchy differs from the taxonomic hierarchy. In most cases, these diagrams show the originating couplet number in a key, but no other details of the key (couplet numbers were introduced in the section on Couplets, Targets and Rows). As will be seen in the Node Structure and Types section, connections for this type are implemented using a targetList in the nodeEntry.

There are several cases in the FPNW where there is a species target in the key to genera for a family. For example in Brassicaceae, one of the species in Brassica, elongata, is a target in the key to genera:

Species acriformis is not a target in any key; instead, it's subspecies are targets in the key to species.

From FPNW: [2/4/2017] Orobanchaceae

The following is a part of the FNA Ranunculus key that has one Characters Set for R. hispidus var. nitidus originating from the key to species and another from the key to subspecies.

Besides this case, subspecies of the following are keyed from the genus instead of their species key:

• Piperia elegans
• Ranunculus acriformis
• Ranunculus aquatilis
• Ranunculus canus

Every once in a while, research shows that a taxon should be moved from one place in the taxonomic hierarchy to another; for example, a species is moved from one genus to another. Howerver, the keying structure may work better if that taxon is keyed out from where it originally was. In an example from Flora of the Pacific Northwest, Sarcobatus vermiculatus is the new name for a species that used to be keyed from the Amaranthaceae key; it still does even though it is now in the Sarcobataceae family, so keying does not follow the taxonomic hierarchy. Note that Sarcobatus is a singleton genus and vermiculatus is a singleton species, so the only target needed is Sarcobatus vermiculatus.

In the FPNW keys, Grayia is a singleton genus and spinosa is a singleton species within Grayia. Grayia is not a target in any key, but is needed in the diagram to show where spinosa fits in the taxonomic hierarchy. The target spinosa has 2 characters sets. One is in the Amaranthaceae key to genera, and the other is in the Atriplex key to species.

The FPNW keys were updated to reflect that six genera are no longer in the Liliaceae family. To make the transition easier for users of the keys, those genera can still be keyed from Liliaceae, as well as from their new families Asparagaceae and Amaryllidaceae. As shown in the following diagram, targets for each of the six genera have two characters sets, the first in the new family's key to genera and the second in the Liliaceae key to genera. In Amaryllidaceae, Galanthus is not a target in the key, but is needed in the diagram because its singleton species nivalis is a target in the key to genera.

From FPNW, this example shows a case where a target (Askellia) is at a higher level than the other targets in the current key (Crepis key to species):

From FPNW, this example shows another a case where a target (genus Aribus) is at a higher level than the other targets in the current key (Boechera key to species). Aribus can also be considered to be a subkey of Boechera (see the Subkeys and Concatenated Keys section):

From FPNW, this example shows a case where the target (Hydocotyle) has Characters Sets originated both in Araliaceae and Apiaceae, and is a target both in the Apiaceae fruit-based and vegetative-based keys to genera.

Localized Keys and Predetermined Characteristics

The first step in using the FNA keys to determine the family of the specimen. The location of where that specimen was collected limits the possible families; this type of key localization is easily understood.

The key to taxa in a family can also be localized. Since some of the paths through the key will lead to taxa not in a given location, there must choices for some couplets that also do not lead to the location.

By tracing every possible path through the key for each taxa in the family (see Characters Sets and Paths), each couplet choice can be associated with a list of locations for taxa following that lead. Therefore, for a given location, the only allowed paths are those that either those through couplets with your location for either choice or through couplets with just your location for one of the choices; that is, if your location is not on the list of locations for a couplet choice, the only possible path is through the other choice.

The Alismataceae key is moderate sized, and the taxa in the family are widely, though not evenly, dispersed in North America. The following diagram for the key shows how it would be localized for taxa in Washington state. The couplet characters are not shown, but the couplet numbers are the same as those for the online key and for its subkeys.

It is generally not worthwhile to use locations lists with printed keys because lists are usually too long to print and too long for the user to look through the list. But they could be used with online keys and with keying apps for smartphones and tablets; the user would specify the location (or locations), and they would be presented with a localized key. As the user traverses the key, they would be told when their path passes a couplet that could be skipped, and the user would usually verify that their specimen has the characters of the choice in the path taken. For example, in the above example, before getting to couplet 2 (the first couplet where they need to make a choice), they would be asked whether their specimen has the characters in the 1+ couplet choice.

Creating good localized keys depends on accurate species location information. The webpage describing the regional keys for the Jepson eflora notes that, because of this, the key for larger area may need to be used to key out some species.

Predetermined Characters - Just like being able to localize a key, a key can be pre-processed for a given morphological character that is used to differentiate targets in the key; the only allowed paths are those that result in targets that have that desired character, simplifying key traversal.

For example, suppose you want to use the Ericaceae Kalmia key to key out a specimen that has alternate leaves.  Instead of using the key

1        Petals distinct nearly their entire lengths.                                                       7 buxifolia

+        Petals connate ca. 1/2 to nearly their entire lengths                                       (2)

2 (1)   Leaves opposite; inflorescences terminal, corymbiform racemes or umbels (3)

+        Leaves alternate (rarely opposite) or in whorls; inflorescences solitary

          flowers or fascicles, racemes, or panicles                                                      (5)

3 (2)   Midribs of leaf blades with purple, clavate trichomes; seeds 1.5-2.2 mm.     6 polifolia

+        Midribs of leaf blades without trichomes; seeds 0.5-1.4 mm                           (4)

4 (3)   Capsules 5-locular; petals 7-9 mm, shallowly cleft; stamens 10.                   5 microphylla

+        Capsules 2-3-locular; petals 3-5 mm, cleft ca. 1/2 their lengths; stamens 5. 8 procumbens

5 (2)   Leaves usually in whorls of 3 (rarely alternate or opposite)                           2 angustifolia

+        Leaves alternate or seemingly whorled                                                           (6)

6 (5)   Leaves deciduous; petals white with red band adaxially.                               3 cuneata

+        Leaves persistent; petals white to pink or red                                                (7)

7 (6)   Plants 8(-12) m; leaf blade surfaces glabrous adaxially (only midrib

           puberulent), 4-12 cm; inflorescences terminal panicles                                1 latifolia

+        Plants 0.6(-1.2) m; leaf blade surfaces usually hairy, 0.5-1.4 cm;

           inflorescences solitary flowers or, sometimes, fascicles or racemes,

           scattered along stem in leaf axils.                                                                 4 hirsuta

if this key had been pre-processed for alternate leaves, then you could use this smaller key

1        Petals distinct nearly their entire lengths.                                                       7 buxifolia

+        Petals connate ca. 1/2 to nearly their entire lengths                                       (2)

2 (1)   Leaves usually in whorls of 3 (rarely alternate or opposite)                           2 angustifolia

+        Leaves alternate or seemingly whorled                                                           (3)

3 (2)   Leaves deciduous; petals white with red band adaxially.                               3 cuneata

+        Leaves persistent; petals white to pink or red                                                 (4)

4 (3)   Plants 8(-12) m; leaf blade surfaces glabrous adaxially (only midrib

           puberulent), 4-12 cm; inflorescences terminal panicles                                1 latifolia

+        Plants 0.6(-1.2) m; leaf blade surfaces usually hairy, 0.5-1.4 cm;

           inflorescences solitary flowers or, sometimes, fascicles or racemes,

           scattered along stem in leaf axils.                                                                 4 hirsuta

For this method to be successful, work would be needed to parse the couplet leads, which can have ambiguous syntax, so it is not clear that use of predetermined characters would be cost effective.  However, it may offer an alternative to creating interactive multi-access keys while offering the major advantage of multi-access keys: most characters of a sample do not need to be examined in a predetermined order.