Iris prismatica |
Iris lacustris |
|
---|---|---|
slender blue iris |
dwarf lake iris |
|
Rhizomes | superficial or only slightly buried in peaty soil, cordlike portions usually 1-branched, 40 cm × 2–5 mm, bearing scalelike leaves at nodes; nodal roots absent. |
with proximal cordlike portion 0.8–2 dm × 2 mm, bearing brown, scalelike leaves and rarely roots, distal portion enlarging to 3–5 × 0.8–1.2 cm, producing fibrous roots, 2–3 brown, sheathing, bractlike leaves, then 8–12 green foliage leaves; usually 2 cordlike rhizomes produced from apex as new growth begins in spring. |
Stems | simple or 1–2-branched, 3–8 dm. |
simple, 0.8–4 cm. |
Leaves | basal with blade slightly ribbed, 3–6 dm × 0.2–0.5 cm; cauline 1–4, erect. |
basal with blade broadly linear at anthesis, slightly falcate, 4–6 cm × 6–8 mm, enlarging to 16 cm × 10 mm; cauline with proximal 1–2 resembling basal leaves, 4–6 cm, distal 2 more sheathing of stem, exceeding spathes. |
Inflorescence units | 1–3-flowered, branch units 1–2-flowered; spathes pale brown, narrowly lanceolate, 2–4 cm, scarious or partially membranaceous. |
1(–2)-flowered; spathes green, outer closely sheathing inner and enclosing ovary, slightly keeled at midrib, 4.5 cm, ± equal, margins scarious. |
Flowers | perianth pale blue or blue-violet; floral tube 0.2–0.3 cm; sepals pale violet, veined deep violet basally, ovate, 4–5 × 1.3–2 cm, base abruptly attenuate; petals lavender, oblanceolate, 3.5–4.5 × 0.7–1.5 cm; ovary trigonal, sharply angled; style arched, narrow, 2–3 cm, crests divergent, quadrate, 0.5–0.7 cm, margins serrate; stigmas sharply triangular; pedicel somewhat flattened, 3–7 cm, exserted from spathe. |
perianth sky blue; floral tube dull yellow, funnelform, 1–2 cm, dilated upward to 4–5 mm diam.; sepals 2–2.3 × 0.8 cm, tapering gradually into claw, apex emarginate, signal white with deep violet margin, with 3 yellow and white, toothed, low ridges; petals spreading, narrowly oblanceolate, 1–1.5 × 0.4–0.5 cm, shorter and narrower than sepals, apex emarginate; ovary sharply trigonal, 0.8–1 cm; style 1–2 cm, crests linear to semiovate, 4 mm, margins crenate; stigmas rounded, margins entire; pedicel 0.6–1.5 cm. |
Capsules | sharply 3-angled, almost winged, 3–4 × 1.2–1.4 cm, concave faces 6–14 mm wide. |
roundly triangular, 1.2 × 8 mm, enclosed in spathes. |
Seeds | in 1 row per locule, buff to dark brown, pyriform, with convex sides, 3–4 mm, smooth. |
dark brown, with white appendage spiraled around seed, ca. 3 mm, quickly drying when exposed to air. |
2n | = 42. |
= 32, 42. |
Iris prismatica |
Iris lacustris |
|
Phenology | Flowering Apr–Jul. | Flowering May. |
Habitat | Swampy, peaty soil | Moist, sandy gravel, limestone shores of lakes |
Distribution |
AL; CT; DE; GA; KY; MA; MD; ME; NC; NH; NJ; NY; RI; SC; TN; VA
|
MI; WI; ON |
Discussion | Several authors have described Iris lacustris simply as being very similar to I. cristata, but smaller in every detail. W. R. Dykes (1913) said, “This name may be retained as that of a local form or variety but it hardly deserves specific rank.” He treated the taxon as I. cristata var. lacustris. R. C. Foster (1937) discussed the relationship between I. cristata and I. lacustris in detail, and recognized the latter at specific rank. He stated, “It is interesting to note that it has been recorded in several localities on or near the Bruce Peninsula, Ontario, that home of so many pre-Wisconsin relics. Professor Fernald informs me that he has seen it growing there in some abundance on the upper levels of the sandy beaches. Quite probably, it is present there, not as a newcomer, but as a relic.” However, G. L. Hannan and M. W. Orick (2000) concluded that I. lacustris is a product of some post-glacial invasion or introduction of a plant or seed of I. cristata that has developed its own very stable and quite unvariable character. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
|
Source | FNA vol. 26, p. 395. | FNA vol. 26, p. 378. |
Parent taxa | Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Prisimaticae | Iridaceae > Iris > subg. Limniris > sect. Lophiris |
Sibling taxa | ||
Synonyms | I. cristata subsp. lacustris, I. cristata var. lacustris | |
Name authority | Pursh: Fl. Amer. Sept. 1: 30. (1814) | Nuttall: Gen. N. Amer. Pl. 1: 23. (1818) |
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