Glossary by Dr. Donald Spoon, with annotations by Dr. Spoon.

Go to original word document sent by Dr. Donald Spoon

List of terms:

Definitions:

---- Alelle. A distinct form of a gene producing a specific trait.

An example is the anthocyanin flower patterns (dominant no pattern, recessives plicata, luminata, and glaciata) at the plicata locus. In tetraploid bearded irises there may be only four different alleles on the four homologous chromosomes at the same gene locus, such as the plicata locus. Dominant alleles (Pl for no plicata pattern) require only one allele or dose (Pl,pl,pl,pl,) of the four doses to be expressed. Sometimes, each additional dominant dose makes the trait more or less prominent by a dosage effect as with the dominant inhibitor (Is) of anthocyanin only in the standards. The recessive alleles usually require four doses (pl,pl,pl,pl) to be expressed unless the other alleles are recessives, than there can be a peck order or an overlapping expression of the recessive alleles. Some dominant alleles at the same locus are codominant producing a mixing inheritance with a trait intermediate between the two dominant traits. Likewise, some recessive alleles at the same locus are corecessive with the traits overlapping equally or unequally creating an intermediate trait. The colloquial term for allele is factor.

---- Allopolyploid . Triploid, tetraploid, or octaploid hybrid having sets of chromosomes with nonhomologous structure from different species.

In the autopolyploid all sets of chromosomes have similar, homologous chromosomes.

---- Alternation of Generation . In plants where the spore forming sporophyte repeatedly follows the gamete producing gametophyte.

With combination the reduced chromosomal numbered male and female gametes redouble the chromosome number to produce the zygote. The zygote develops into the embryo that develops into the new sporophyte plant that by meiosis (reduction and division) produces microgametophytes that produce the male gametes and macrogametophytes that produce the female gametes.

---- Amphidiploid . Hybrid from two tetraploid species each contributing two sets of chromosomes in their gametes for a total of four sets in the zygote. The two diploid sets are so different morphologically that they do not independently assort at meiosis, thus the tetraploid hybrid behaves more like a diploid.

---- Aneuploid . Hybrid that lacks or adds one or more chromosomes in the sets of chromosomes.

The result is a chromosome number less or more than the multiple of sets would dictate. The mismatches at meiosis when the homologous chromosomes line up and synapse may make the hybrid sterile.

---- Arilbred, AB. An iris cultivar that is at least 1/8th aril (oncocylous or regalia bearded irises) crossed with other bearded irises.

---- Amoena. (ah me nut) White standards and colored falls.

It is difficult to give an operational definition of the term amoena, meaning ‘pleasing’. Originally, amoena meant only cultivars with white standards and anthocyanin pigmented falls, and later just colored falls that included pink and yellow amoenas. Possibly, the best modern description is anthocyanin pigment in the falls and none in the standards. In such an amoena, the standards can be white, cream, yellow, pink, peach, red-orange, or orange. Also, in the falls the anthocyanin pigment pattern can overlay any carotenoid pattern. Amoena luminatas have only the fall’s anthocyanin pattern displayed as a luminata color pattern. Amoena plicatas have a plicata color pattern only in the falls. The anthocyanin amoena patterns are produced by two different genes; in one, the pattern is recessive requiring four recessive doses for expression and in the other, the pattern is dominant with dosage effects so that only with four doses (Is Is Is Is) are the standards free of anthocyanin pigment. Complicating the usage of the term, there are patterns also called amoena in the carotenoid pigment colors that require four recessive alleles for the standards to be white. These are named for the falls color, such as yellow amoena, pink amoena, and orange amoena.

---- Anthocyanin pigment . The main water soluble pigment present in the central vacuole of the epidermal cells that give the iris flower their nearly black, violet, blue, light floridor blue, maroon, brick red, brown, tan, and orchid pink coloration.

There are several groups of these water soluble, cell-sap pigments that are lumped together under the term ‘anthocyanin’ that is the major group.

---- Anthers. Male structure bearing two elongate lobes filled with maturating pollen.

When fully developedthe lobes rupture or dehisce releasing the powdery pollen grains. The anther plus its supportive filament is the stamen.

---- Autopolyploid. Hybrid with 4 or 8 sets of chromosomes in which all sets are homologous with similar structures.

Autopolyploids are produced by natural processes or chemical induction.

---- Backcross . Inbreeding when cultivar or species hybrid is crossed as pod or pollen parent on either of its parents.

---- BB. Border bearded irises , 16-27.5” (41-70 cm) tall stalks that bloom with the tall beardeds (TBs) and MTBs.

Border beardeds are mostly from TB breeding. With esthetically pleasing proportion Border Beardeds have larger and wider flowers as well as thicker stalks than the MTBs of similar stalk heights. A seedling with stalks shorter than 27.5” (70 cm) yet TB sized flowers is best used for further hybridizing and not introduced unless it carries unique traits or color of considerable value to other hybridizers. (Ben Hager introduced his excellent parent for modern formed, reliable rebloomers, the very short TB ‘Bonus Mama’)

Under Construction. See Attached original at beginning of page

-- BobPries - 12 Feb 2019

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