MEKA
– An introduction to the use of Meacham’s Multiple-Entry Key Algorithm
by
This introduction to the
use of the general purpose interactive Multiple-Entry Key Algoritm
(MEKA) is merely intended as a demonstration of the user friendliness of MEKA
for WINDOWS (version 3.00). My own key to Crataegus in western parts of
the the
I have added my Index File of Character States, CRATAEGUS.IND, with information on it’s codes,
because this file type is not well documented in the MEKA documentation supplied
by Dr. Meacham (MEKA
— NEW: Meka Version 3.1 now available from the Jepson Flora Project).
NOTICE:
If you want to see the following images in full size - click on the images!
When a key has been
selected the following two sequential opening screens appear: 
Click OK
Then this screen appears in
the CRATAEG key
When you have clicked OK once more, you enter the key.
If there is an Index file
(*.ind) the Index to Characters States
appears on the screen. You may use this index when determining your material
or you can choose to use
the entire list of Score Character States
and Matching Taxa by clicking on Score and Match.
-- In MEKA keys without an Index to Character States
(i.e. no *.ind is present) the list of Score
Character States automatically appears! In this case All characters of the General
column of the Index to Character States is
used, and Mode is set to Show counts, i.e., the number of taxa having a
certain character state, and, thereby, making it easier to select the best
character states during the determination (see above).
Open the Matching taxa window by clicking on the Match button
When you have decided how
to use the key simply highlight the character state you want to use first in
the determination, e.g. leaf blades (fl shoots) up
to 4 cm long, then click the Present button
(if this character state is present!).
Notice that the number
in Taxa Match window is reduced from 93
to 72 (equal to the count in []).
Now, select a new character
state. Our specimen has: lower surface of lamina
sericeous
and the number of taxa
remaining is reduced to two taxa only, viz.: C.
pycnoloba and C. Xpeloponnesiaca.
Our specimen has fruits with persistent bracts. Consequently, bracts persistent is scored,
and the specimen is
detemined as belonging to C. pycnoloba.
Highlight C. pycnoloba, and then click on
the Image button to see a drawing or a
photograph of C. pycnoloba.
Click on the Next button to see additional illustration(s).
or click on the Previous button to see the previous illustration,
or the Close button, if you do not need
to view further illustrations.
Finally, click on the Notes button in the Matching
Taxa window to see written information on C. pycnoloba.
If you decide to use the Differentiating Characters mode instead of the Index or Score
mode, the determination may be done even faster!
When this mode is
chosen, the character states are sorted as shown below:
Our specimen has fruits
with persistent bracts (a state found in only two of the taxa included in this
key). When bracts persistent is scored, a
new list of Differentiating Character States appears,
and the character state lower surface of lamina sericeous is scored
for our specimen. The specimen is once again determined as belonging to C. pycnoloba
FURTHER
INFORMATION
For detailed introductions
to MEKA ver. 3.00 consult the MEKA webpage (MEKA), as well as the documentation supplied with
the program!
EXAMPLE OF A MEKA INDEX
FILE (*.ind)
Explanations are given in variously coloured […]
5 20 0 [5=no. of
headlines/columns in Index. – 20=size code of Index, i.e., width of Index
window (30 wider than 20). – 0=buttons abute horizontally (1=not so)]
General [1. headline]
7 [number
of buttons (characters) under 1. headline]
general distrib. [button (character) text]
185 243 [range/interval of number codes of character states]
Europe [button (character) text]
185 205 [range/interval of number codes of character states]
Russia/Caucasia
[button (character) text]
208 213 [range/interval of number codes of character states]
Asia [button (character) text]
214 232 [range/interval of number codes of character states]
N Africa [button (character) text]
233 238 [range/interval of number codes of character states]
N America [button (character) text]
239 243 [range/interval of number codes of character states]
cultivation [button (character) text]
244 245 [range/interval of number codes of character states]
Twigs [2. headline]
2 [number of buttons
(characters) under 2. headline]
twigs [button (character) text]
1 14 [range/interval of number codes of character states]
thorns [button (character) text]
8 14 [range/interval of number codes of character states]
Leaves [3. headline]
7 [number of buttons
(characters) under 3. headline]
leaf blades [button (character) text]
15 70 [range/interval of number codes of character states]
lamina/size [button (character) text]
15 21 [range/interval of number codes of character states]
upper surface [button (character) text]
-2 22 29 51 51 [range/interval of number codes of character states -- -2 indicates TWO
ranges]
lower surface [button (character) text]
30 37 [range/interval of number codes of character states]
lobes/veins/margin [button (character) text]
38 61 [range/interval of number codes of character states]
petiole [button (character) text]
62 70 [range/interval of number codes of character states]
stipules [button (character) text]
71 84 [range/interval of number codes of character states]
Infl./flowers [4. headline]
8 [number of buttons
(characters) under 4. headline]
inflorescence [button (character) text]
85 98 [range/interval of number codes of character states]
flower [button (character) text]
99 147 [range/interval of number codes of character states]
bracts [button (character) text]
99 112 [range/interval of number codes of character states]
hypanthium [button (character) text]
113 117 [range/interval of number codes of character states]
sepals [button (character) text]
118 128 [range/interval of number codes of character states]
petals [button (character) text]
129 133 [range/interval of number codes of character states]
stamens [button (character) text]
134 142 [range/interval of number codes of character states]
styles [button (character) text]
143 147 [range/interval of number codes of character states]
Fruit/nutlets [5. headline]
6 [number of buttons
(characters) under 5. headline]
fruit [button (character) text]
143 184 [range/interval of number codes of character states]
flesh [button (character) text]
174 179 [range/interval of number codes of character states]
hypostyle [button (character) text]
181 181 [range/interval of number codes of character states]
nutlets/fruit [button (character) text]
143 147 [range/interval of number codes of character states]
nutlets/surface [button (character) text]
182 184 [range/interval of number codes of character states]
pedicels [button (character) text]
-2 97 98 180 180 [range/interval of number codes of character states -- -2 indicates TWO ranges]