1924, Iris Cristata

Addisonia page 63, plate 320, 1924 IRIS CRISTATA

Crested Dwarf-iris

Native of the southeastern United States

Family Iridaceae, Iris Family

Iris cristata Ait. Hort, Kew. 1: 70. 1789.
Iris odorata Pers. Syn. PI. 1: 53. 1805.
Neuheckia cristata A.M^\d,Bot.Z&it. 21: 297. 1863.


Our so-called dwarf-irises represent a group quite different from the larger blue-flags. The groups differ from each other not only in the structure of the flowers and the fruits, but also in the habitats. The natural habitat of the blue-flags is wet; that of the dwarf-irises is dry. Consequently there is a difference in the anchorage and stem-systems. The larger blue-flags have cord-like fleshy roots and stout fleshy rootstocks, while the dwarf-irises have fibrous roots and coarse-wiry rootstocks.

This dwarf-iris flourishes in the plantations of the New York Botanical Garden, as well as in other places farther northward than its natural range. This fact leads one to suspect that the plant never regained all the ground it may have lost during the ice age. Within its range it is most abundant along the main drainers of the highlands. Along these highways, as it were, in post-pleistocene times, it reached the Atlantic seaboard on the east and the Trans-Mississippi country on the west. As there are no great erosion highways running northward from the old Appalachian plant reservoirs, the plant's progress in that direction was, evidently, checked or blocked.

The crested dwarf-iris, however, is one of the few flags that has left a tangible trail behind it in its escape from the old Appalachian Highlands. It spread radially from the high altitudes into the Piedmont and Coastal Plain, and it still maintains a foothold from the higher mountains to near sea-level.

Iris cristata is of wide geographic distribution, in the southeastern United States south of Pennsylvania and Missouri, and consequently of varying habitats. Cliffs, bluffs, rocky hillsides, ravines, and woods are among its native haunts. Plants with albino flowers have been found.

The origin of the type specimens of the crested dwarf-iris is not known. Alton, who first describes it botanically, records that it was introduced from North America into England by Peter Collinson in 1756. It was probably secured in the southern Atlantic States by Collinson's chief explorer, John Bartram, or by one of the half-dozen plant collectors who were then active in that region.

The method of seed-dispersal in the dwarf-irises is quite different from that of the large blue-flags. The corky-coated seeds of the blue-flags merely float away or about on the water of the plant's habitat. Each seed of the dwarf -irises, inhabitants of dry places, has a viscid appendage — aril — by which it may adhere to the feathers of birds or fur of animals, and thus be disseminated.

The crested dwarf-iris has coarse-wiry branching rootstocks with tuberlike thickenings. The branches are dimorphous; the foliage ones very short, with three to six leaves which are closely imbricate at the base and with sabre-like blades one to twelve inches long, the inner much the longer; the flower-branches are mostly one to three inches long, with the small dirk-like leaves more or less enfolded, but not imbricate at the base. The flowers are solitary or two together, faintly scented, exceeding the involucre formed by the upper leaves of the flower-stalk. The pedicel is about as long as the ovary in anthesis, or longer. The hypanthium, surrounding the ovary, is sharply three-angled and with a slight ridge on each face. The perianth-tube is mostly one and three quarters to two and three quarters inches long, very slender, broadly funnelform at the top.

The three sepals are cuneate-spatulate to narrowly obovate, one and a quarter to one and a half inches long; the blade mainly lavender, dark or pale, with a white blotch bordered with violet; the claw is shorter than the blade, with a crest of three beaded ridges, the median one yellow and running to the base of the claw, the lateral ridges yellow with white edges, all extending up into the blotch in the blade. The three petals are spatulate, somewhat shorter than the sepals, lavender, except the deeply channeled purple claw. The three stamens are one half to three quarters of an inch long, w4th the subulate filament tinted with lavender and the yellow anther longer than the filament. The style is filiform, about as long as the perianth-tube. The three style-branches are narrowly cuneate above the slender claw, about one inch long, lavender, more deeply shaded along the midrib. The style-appendages are semi-ovate, about a quarter of an inch long, blunt, undulate. The stigma is semicircular, not lobed, minutely erose. The capsules are ellipsoid or oval, varying to ovoid or obovoid, one half to three quarters of an inch long, often minutely beaked with the persistent style-base, three-lobed, the lobes with a slight median groove, each sinus with a minute groove. The mature pedicels are about as long as the capsules or longer. The seeds are nearly or quite one sixth of an inch long, oval or obovoid, but slightly inequilateral, brown, with the aril-tip curled over the top of the seed-body.

John K. Small.

For more information on historic Irises visit the Historic Iris Preservation Society at

-- BobPries - 2014-12-08