Manual de Plantas de Costa Rica |Plan of the Manual| pia | 
mal treatment in this Manual, and should not be taken as absolute. In some cases, these 
totals are subdivided into native and exotic taxa (where the latter are fully treated). Fol- 
lowing these totals, published family treatments in two major ongoing floras are cited 
(when available) in shorthand form, as follows: FC = Flora costaricensis; FM = Flora 
mesoamericana. 
Keys 
An analytic key, like the ones used in the Manual, is basically a list of contrasting or 
excluding propositions that (when followed) help to identify something. To the great- 
est extent possible, the keys in the Manual are artificial (with an emphasis on similari- 
ties and differences, rather than relationships) and field-friendly. Obvious vegetative 
features have been favored over technical details, although in some groups (e.g., Or- 
chidaceae) heavy reliance upon floral characteristics could scarcely be avoided. Fea- 
tures appreciable only on dried specimens (e.g., color and texture of leaves on drying) 
have been avoided, except occasionally as supplementary characters. 
Identification of an unknown plant to species level may require successive use of 
keys to major groups, families, genera, and species, always in that order (narrowing to 
lower and lower categories). If any of these categories is already known, the key to that 
and all higher-order categories may be skipped. All keys in the Manual are dichoto- 
mous and indented. Use of the keys is straightforward. The user is presented with num- 
bered sets (couplets) of two alternatives (leads) and decides, in each case, which of the 
two leads better fits the specimen in hand. The two leads of the first couplet are desig- 
nated as | and 1’, those of succeeding couplets as 2 and 2’, 3 and 3’, etc. Having made 
a decision, the user then moves on to the first couplet nested (indented) below the cho- 
sen lead and repeats the procedure. One should always read both options carefully, 
comparing them with the plant. This is continued until the name of a taxon (family, 
genus, or species) appears at the end of the chosen lead and there are no additional 
nested couplets. Occasionally, an instruction, rather than a taxon name, will appear in 
this situation (e.g., “Proceda a la copla 37”). 
N.B.: Although the user will always progress to a higher number, it will not neces- 
sarily be the present number + |. For example, if lead 1 is chosen for the first couplet, 
the next couplet will indeed be couplet 2; however, if lead 1’ is chosen, the next coup- 
let may be couplet 3, or some higher number, depending on how many couplets are 
nested under lead 1. On the other hand, if lead 1 directly identifies a taxon, then the first 
couplet under lead 1’ will be couplet 2 after all. The rule is to be guided by the inden- 
tations; however, in some very large keys, the indentation may become so extreme that 
it must be renewed (left-justified) at some point. In that case, both leads of the first 
couplet in a renewed indentation series will be marked at the beginning with a squiggle 
(~). For further insight into the construction and use of keys see, e.g., Bell (1968) and 
Marzocca (1985). 
