Before the fertile C.G. White halfbreds became widely available, many hybridizers struggled to break the fertility barriers that then existed in the world of arilbreds. Occasionally, someone succeeded and some of those breakthrough breeders were widely used. 

When the C.G. White amphidiploids came on the scene and hybridizers realized that they constituted a new fertile family, they became the foundation on which a new artificial species was developed - the one we now call halfbreds. The older breeders went out of fashion. Some justifiably so, but others were merely lost in the excitement of the transition period. The ones for which additional information is available have clickable links.

ARDRUN (H.M. McLeod, 1954). Blend of rose-purple and mulberry shades from Artemis X Gudrun that was counted as a 44-chromosome amphidiploid. Appears to be the source of the korolkowii-type growth pattern of modern arilbreds, introduced to the lines of many different hybridizers through Esther, the Queen. Even though it now has had more descendants introduced than most of the C.G. White amphidiploids, its potential has still not been fully explored. 

BENJAMIN (Sir Cedric Morris, 1950). Blend of lime-green and shades of purple. A regelia-pogon-dwarf hybrid from I. stolonifera x yellow chamaeiris, counted as a 42-chromosome amphidiploid and reportedly fertile, but no registered offspring.

CAPITOLA (Frank Reinelt, 1940). William Mohr X Ib-Mac. AIS Color Class R2D (dark red, feathered blue). Counted as having 43 chromosomes, but functions much like an amphidiploid. Highly pollen fertile, but pods reluctantly. Included here because although some of its descendants have contributed to the halfbred gene pool, most of its registered offspring are quarterbreds and I do believe its full potential as a parent remains unexplored. 

CONGRES (Cayeaux, 1924). No description availble, only pedigree is "RC x Bearded", but it was counted as having 46 chromosomes, and proven fertile. Only registered offspring are quarterbreds: CARIBBEAN SKY and LUNAR MIST, both introduced in 1953.

HOOGIMAC (Eugene Sundt, 1960). Spotless X Ib-Mac. S campanula violet; F spectrum violet, deep violet at tip of near-white beard. Tell, 1960. Reportedly fertile, and counted as a 46-chromosome amphidiploid, but it has no registered offspring.

IB-MAC (C. G. Van Tubergen, 1910). Medium red bitoned blend from I. iberica X I. macrantha, counted as a 44-chromosome amphidiploid. One of the most important early breeders with many registered offspring. Most, however, were quarterbreds - although some served as conduits for I. iberica genes to take their place in today's gene pool. 

IFTAH EL-BAB (David Flesh, 1963). Kalifa Abra X CGW F-2. S erythrite red, veined oxblood, F deeper, patterned deep maroon, bronzy brown beard. Reportedly a 44-chromosome amphidiploid, a second-generation product of C.G. White's lines, with no registered offspring.

ISMALI (Sir Michael Foster, 1909). Bitoned blend from I. iberica X I. pallida, counted as a 46-chromosome amphidiploid. No registered offspring.

KOROLCYP (Louis A. Denis, 1923). No description available, from I. korolkowii X I. cypriana, counted as a 46-chromosome amphidiploid. No registered offspring.

LADY LILFORD (Sir Michael Foster, 1916). Blue-toned white blended with darker tones of blue. I. paradoxa X I. pallida. Counted as a 46-chromosome amphidiploid. Only two offspring were introduced, both quarterbreds:

RIC-IB (Louis A. Denis, bef.1923). Ricardi X I. iberica.  Counted as a 46-chromosome amphidiploid, but noted as obsolete in '39 CL. No other information available.

SHARKSIANA (Earl Roberts, 1959). S white; F white with chartreuse lines; orange-yellow beard. Sharkskin X I. susiana.Counted as a 44-chromosome amphidiploid, no registered offspring.

SPOTLESS (Jacob Sass, 1939). White self from I. hoogiana X Elf Queen. Counted as having 42 chromosomes. Only one registered offspring: HOOGIMAC (Eugene Sundt, 1960). S campanula violet; F spectrum violet, deep violet at tip of near-white beard. From Spotless X Ib-Mac, counted as a 46-chromosome amphidiploid.

ZWANENBURG (Louis A. Denis, 1912). Yellow-toned blend from Lutescens aurea X I. susiana. Counted as a 40-chromosome amphidiploid. All registered offspring are quarterbreds, but could theoretically give fertile seedlings if paired with a compatible amphidiploid.