produced this change. (1) In the earlier publication,
I used a random sampling of the AATT and ATTT
height data, whereas the present analysis uses all
of the available data. (2) I had previously included
arilbreds with more than one-half aril complement in
the analysis, even though I excluded them from the
ABM class. This inconsistency introduced a small bias
toward a lower height limit. (3) Most importantly, the
twenty additional years of data have changed the
distributions slightly. In particular, the median height of
APTT irises has increased slightly.
ARILBREDS OF MORE THAN HALF
ARIL COMPLEMENT
These arilbreds, those in the OB+, OGB+, and
RB+ categories used by the ASI, require special
consideration. In terms of chromosome complement,
they are mostly AAT or AAAT. Many of these irises
are small in height, not because of their bearded
ancestry, but because the aril irises themselves tend
to be small in stature, and these arilbreds are mostly
aril. It would be a mistake to place them in the ABM
category when their affinity is more with the pure arils,
both in ancestry and in garden effect, than it is with the
medians. Therefore, the ABM category is best limited
to irises of one-half aril complement or less.
In contrast, it seemed worthwhile to extend the
ABD category into this realm, as a few have been
produced in this range that are three-quarters aril
and one-quarter I. pumila (AAAP) and do show their
dwarf heritage. Only one AAT iris (and no AAAT) has
been registered at less than 13 inches, so extending
the ABD class into this range causes little disruption.
The diagram below shows how the bearded irises
and arilbreds can be sorted based on height and aril
content.
AND NOW FOR THE DEFINITIONS!
The result of all this philosophical rumination and
painstaking data analysis is the following proposed
definitions:
ARILBRED DWARF (ABD): any arilbred with a
registered height of less than 33 cm (13 inches).
ARILBRED MEDIAN (ABM): any arilbred of one-half
aril complement or less, with a registered height
between 33 and 56 cm (13 and 22 inches), inclusive.
ARILBRED (TALL) (ABT): any arilbred with a reg-istered
height greater than 56 cm (22 inches), or any
arilbred of more than one-half aril complement with a
registered height of 33 cm (13 inches) or greater.
aril content
none < 1⁄2 aril 1⁄2 aril >1⁄2 aril
height
height
70 cm
56 cm
41 cm
33 cm
20 cm
27.5 in
22 in
16 in
13 in
8 in
TB
IB
BB
MTB
SDB
MDB
ABT
ABD
ABM
36 AIS Bulletin Fall 2018