N/A

Spec-X, interspecies hybrid (D. Kramb, 10-NOV-03)

N/A

2n=90 (D. Kramb, 01-SEP-04)

Iris robusta is apparently a naturally occurring hybrid between Iris virginica and Iris versicolor. (D. Kramb, 19-JAN-04)

Plants form dense clumps. Foliage is dark green, stiff with mid-rib, 28" to 32" tall and 1/2" to 3/4" wide. Stalks have 2 to 3 branches with 3 buds per branch, 30" to 36" tall. Flowers are intermediate, later than versicolor, but earlier than shrevei and are better and longer lasting. Standards are more or less the same as in versicolor, upright or flattened, lighter in color than the falls. The falls are larger as in shrevei, horizontal, tips slightly pendulous, depp purple to violet. There is little variation in the same colony. Styelarms are purple in the center and bordered white or pink. Seedpods are cylindrical, sharply triangular, less than half the size of pods of shrevei, and narrower than versicolor. Seed ripens later than versicolor but earlier than shrevei. Seeds are slightly corky, rounded or D-shaped. Seeds are smaller than shrevei, and light brown. They germinate after frost treatment and seedlings will bloom in the second year. (D. Kramb, 01-SEP-04)

The stems and foliage often exhibit black coloration, especially in early spring. (D. Kramb, 19-JAN-04)

Grows best in full sun with wet soil, such as on the edge of a pond. (D. Kramb, 19-JAN-04)

Estimated Zones 4-9. (D. Kramb, 19-JAN-04)

N/A

N/A

Specialty nurseries and water garden centers. (D. Kramb, 19-JAN-04)

Information entered on 01-SEP-04 comes from issue# 60 of the SIGNA bulletin, page 3118. The article was written by Tony Huber of Laval, Canada. (D. Kramb, 01-SEP-04)

Robustas may occur naturally in places where versicolor and shrevei populations overlap. These hybrids tend to give nicer and more vigorous plants when shrevei is 2n=72. When shrevei is 2n=70 the back-crosses are short-lived and sterile due to the unpaired chromosome combination. (D. Kramb, 01-SEP-04)