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.