The character broad leaf (b or e) is independent of the characters in the known linkage groups. This has been tested by growing F2's of from 500-7000 plants. The recombination values and, their errors derived from these data show no significant departures from 50%. The character broad leaf is therefore prorosed as a marker for group eleven.
By similar tests macrocalyx has been found to be independent of all known groups and also shows no linkage with broad leaf. It is therefore proposed that macrocalyx (mc) be used as a marker for linlage group twelve.
The tenth chromosome character wilty foliage (wt) is linked with leafy infloresence (lf) and jointless pedicel (j) in the fifth chromosome. Limited data indicates that it is on the opposite side of jointless to the locus of green stem (a\1\). Backcross material is being prepared to confirm these locations. Nipple-tip (n) has been shown to be linked with wt but there is little data concerning its linkage relations with group five genes. The distance between j and wt is so great that if n is on the distal side of wt the linkage would be hard to detect. It is proposed that wt and n both be taken out of group ten and put in group five. It is further proposed that narrow cotyledon (nc) which so far has proved independent of other groups, be tentatively used as a marker for group ten.