Iris probstii C.A.Wilson, 2020

Wilson, Carol A., 2020, Two new species in Iris series Chinenses (Iridaceae) from south-central China, PhytoKeys 161, pp. 41-60 : 41

Iris probstii C.A.Wilson sp. nov. Figures 2D-F , 5

Diagnosis.

Morphologically similar to I. henryi , the new species differs in having wider sepals (ca. 7 mm versus 4 mm) and style branch lobes that are shorter (ca. 2-3 mm versus 6 mm).

Type.

China. Guizhou Province: about 24 km south of Yanhe on road to Xiushan, 970 m, 28°25.643'N, 108°42.044'E, 24, July 2003 (fl), voucher from cultivated material, D. Probst CPC24.7.03.1 (holotype: UC!; isotypes: PE!, E!).

Description.

Small evergreen herbaceous plant with aerial flowering stems shorter than basal leaves. Bracts, cauline leaves, base of basal leaves ± tinged with red. Rhizomes short (<4 mm), branched, hidden by leaf remains. Stolons present. Roots highly branched distally with small tubers. Basal leaves distichous, linear with acute apex, bright green, slightly glossy on upper surface, dull green on lower surface, leaf edges obscurely membraneous, 12-40 cm long, 0.4-0.6 cm wide, veins slightly thickened; crowded in clumps. Flowering stem ca. 15 cm with 2 (3) cauline leaves on lower half. Inflorescence with two opposite bracts (spathes) subtending 2 (3) flowers, terminal flower opening first with a single bract subtending each subsequent flower; lower bracts ± unequal, 3.5-6 (7) cm long, 0.4-0.5 cm wide; pedicels long (3-4.5 cm) and slender. Flowers cream with light violet, open, ca. 3 cm diameter, radial with petals slightly angled upward, sepals horizontal and recurved distally; floral tube 0.3-0.4 cm; sepals cream adaxially, light yellow abaxially, narrowly obcordate, ± shallow apical notch, narrowed at base, 2.2-2.9 cm long, 0.6-0.9 wide, obvious yellow-orange median ridge, purple spot beginning at ca. midpoint and extending distally beyond ridge with two bright yellow patches flanking ridge distally; petals cream with light violet tint that is more prominent along median, narrowly spathulate, 1.8-2.2 cm long, 0.6-0.7 cm wide, clawed in lower 1/4; stamens cream, ca. 1 cm long, anthers = filaments; style branches medium violet, 1.2-1.5 cm long, 0.3-0.4 cm wide, bi-lobed distally, light violet lobes ca. 0.2-0.3 cm long with several teeth, stigma broad, slightly rounded. Capsule rounded with short apical beak. Seed light to medium brown, ca. 0.4 cm, with conspicuous white appendage. Flowering: April to May.

Distribution and ecology.

Iris probstii is currently known from two locations south of Yanhe in Guizhou Province China (Fig. 6 ) at about 800 to 1,000 m and a third unverified location about 165 km south of Yanhe. This third site, southeast of Tongren, Guizhou, China near Minhezhen (Minhe town), is based on photographs taken by C. Yang in 2016 and uploaded to the Plant Photograph Bank of China (http://ppbc.iplant.cn/tu/6166544). A study of herbarium records from CVH, KUN, and PE did not reveal additional collections but it is likely that this new species occurs in other areas within this region. The species occupies open slopes along edges of rice paddies or under low pine woods in grassy sites associated with rocky, karst soils.

Etymology.

The new species is named in honor of the U.S. horticulturist, Darrell Probst, in recognition of his work to expand our knowledge of species from series Chinenses in their native habitats.

Preliminary conservation status.

Following the criteria and categories of IUCN (2012), Iris probstii is given a preliminary status of Vulnerable (VU D2) due to its restricted area of known occupancy (<20 km2) and number of locations (<5). The area of occurrence does not have protected status. If the third location is verified and vouchered the conservation status might change.

Other specimens examined.

China. Guizhou Province: about 55 km south of Yanhe on road to Xiushan, 825 m, 28°19.651'N, 108°41.390'E, 9, January 2002 (fl), D. Probst CPC9.1.02.2 (photo of living plant, UC).

Notes.

D. Probst collected a small rhizome segment at the second site that he grew but did not voucher. An image of the plant was obtained for documentation and deposited in UC. A specimen voucher will be made and also deposited at UC when the plant reflowers.

Figures

Figure 2. Images A-C I. dabashanensis D-F I probstii. A Habit B inflorescence C flower D habit E inflorescence F flower (Photos B-F C. author; A Mark McDonough).

Figure 5. Illustration of I. probstii. A Habit B inflorescence C sepal D petal E style branch, anther F fruit (Sources: A-E D. Probst CPC 24.7.03.1 (UC); F photograph by M. Schafer and J. Sacks, photographs available from author).

Figure 6. Map of known distribution for I. probstii in gray outlined in black.