Key to Arisaemas of Japan

From the Flora of Japan (Ohwi)

1A. Spadix-appendage filiform, long-exserted from the spathe

2A. Normal leaves 2; spadix-appendage 10-15 cm long, 2.5-3.5 times as long as the spathe tube; terminal leaflet not longer than lateral ones A. negishii

2B. Normal leaf solitary; spadix-appendage longer than 15 cm

3A. Terminal leaf much shorter than the adjacent lateral ones; psudostem more than 40 cm long; spathe nearly green A. heterophyllum

3B. Terminal leaf as large or larger than adjacent lateral ones; psudostem nearly wanting; spathe dark reddish purple

4A. Spathe-blade with a T-shaped white mark inside; scape rising near base of petiole A. kiushianum

4B. Spathe-blade without a T-shaped white mark inside; scape arising above base of petiole

5A. Enlargement at base of spadix-appendage densly wrinkled A. thunbergii

5B. Enlargement at the base of spadix-appendage smooth A. urashima

1B. Spadix-appendage terete or clavate, obtuse or sometimes capitate at the apex, shorter than blade of the spathe

6A. Spadix-appendage gradually passing into the floriferous part; spathe and spadix-appendage different in staminate and pistillate plants A. heterocephalum

6B. Spadix-appendage truncate at base; spathe and spadix-appendage equal or nearly alike in staminate and pistillate plants

7A. Spathe-blade saccategaleate; leaflets always 3, filiform at apex,rather thick, lusterous above, entire A. ringens

7B. Spathe-blade spreading, declined, or ascending anteriorly

8A. Leaflets always 3, with many sub-translucent papillae on margin; Spathe-blade acuminate A. ternatipartitum

8B. Leaflets 3-15, pedate, margins entire or loosely undulate to toothed; Spathe-blade radually or abruptly acute

9A. Normal leaf solitary (rarely 2)

10A. Spadix-appendage rather stout, 3-10 mm across, terete, or gradually thickened toward apex; Spathe-blade deltoidovate, 3-5 cm wide

11A. Scape 3-10 cm long

12A. Lateral leaflets 2 (3) on each side, nearly radiate; rachis slightly developed

13A. Spathe-blade obliquely ascending, 5-6 cm long A. robustum

13B. Spathe-blade strongly declined over the spathe, 8-10 cm long A. ovale

12B. Lateral leaflets 3-8 on each side; rachis, at least the lower part, well developed

14A. Leaflets obvate, abruptly short-acuminate; habitat: Izu Peninsula A. izuense

14B. Leaflets lanceolate to oblong-obovate, tapering toward apex; Kinki District and westward

15A. Spathe-blade oblong-ovate, abruptly long-acuminate, strongly declined over spadix; spadix-appendage cylindric-clavate, slightly thickened at apex A. suwoense

15B. Spathe-blade deltoid, abruptly narrowed from top of tubular part, erect, the apex gradually elongated to a linear tip; spadix-appendage narrowly cylindric terete A. simense

10B. Spadix appendage thickened at both ends or at least at the base, the median and sometimes apical part narrow. 1-2 mm thick; Spathe-blade broadly deltoid-lanceolate to narrowly deltoid-ovate, 2-3 cm wide; leaflets 7-19

16A. Spathe entirely green, papillose on margin A. yoshiokae

16B. Spathe usually purplish, entire

17A. Spathe-blade 7-10 cm long

18A. Leaflets 9-11; Spathe-blade linear, ovate, gradually acuminate A. iyoanum

18B. Leaflets 7-9

19A. Spathe-blade ovate-lanceolate, long-acuminate, dark purple with 4 white stripes; Honshu (Harima Prov.) A. seppikoense

19B. Spathe-blade oblong-lanceolate, subabruptly acute, light purple brown; Aki A. akiense

17B. Spathe 3-6 cm long

20A. Spathe-blade, at least in part, dark purple, 5-6 cm long, deltoid-lanceolate A. monophyllum

20A. Spathe-blade greenish, ovate, 3-4 cm long A. maximowiczii

9B. Normal leaves 2, rarely 1 in depauperate individuals

21A. Leaflets 3-5; Spathe-blade abruptly long-acuminate; spadix-appendage capitately thickened at apex A. sikokianum

21B. Leaflets (5-)7-17; spadix-appendage cylindric, slender or cavately thickened at apex

22A. Spathe-blade filiform-elongate

23A. Spadix-appendage thick-cylindric; Spathe-blade dark purple with vertical white stripes A. kishidae

23B. Spadix-appendage clavate, thickened at the apex; Spathe-blade green A. tosaense

22B. Spathe-blade acuminate to longacuminate, not filiform-elongate

24A. Spathe-blade broadly-lanceolate, gradually long-acuminate; spadix-appendage slenderly cylindric

25A. Spathe-blade bent forward horizontally A. longilaminum

25B. Spathe-blade declined and arching over the spadix

26A. Spadix-appendage erect A. angustifoliatum

26B. Spadix-appendage slightly bent forward A. shinanoense

24B. Spathe-blade narrowly to broadly ovate

27A. Spathe-blade densely yellowish papillose inside A. yamatense

27B. Spathe-blade smooth inside

28A. Spathe-blade obliquely ascending or bent horizontally, abruptly short-acute

29A. Plant loosely tufted with numerous young plants; Spathe-blade oval to orbicular-ovate A. proliferum

29B. Plant solitary; Spathe-blade ovate

30A. Spadix-appendage thick clavate A. speirophyllum

30B. Spadix-appendage linear or cylindric A. peninsulae

28B. Spathe-blade declined above; longacuminate

31A. Spathe-blade oblong-deltoid, tapering from base; spadix-appendage cylindric, the apex as broad as the other part

32A. Spadix-appendage slenderly cylindric or linear

33A. Spadix-appendage linear; Spathe-blade obliquely declined only at tip; leaflets 9-18, often serrulate; Honshu A. angustatum

33B. Spadix-appendage cylindric; Spathe-blade declined; leaflets 11-13 in the lower one, entire; Kyushu A. koshikiense

32B. Spadix-appendage cylindric, rather thick, to 8 mm across at the base; tublular part of the spathe rather long A. solenochlamys

31B. Spathe-blade broadly ovate to ovate-lanceolate, tapering from below the middle but not from the base

34A. Leaflets palmate on the scarcely developed rachis; scape longer than the leaves

35A. Leaflets 5 A. nikkoense

35B. Leaflets more than 5

36A. Leaflets 5-7, not variegated, narrowly oblong, entire or serrate; spathe auricles very distinct A. stenophyllum

36B. Leaflets 8-14, with a broad white line along the midrib, linear-lanceolate, always undulate on the margin; spathe auricles narrow and rather inconspicuous A. undulatifolium

34B. Leaflets pedate on the well-developed rachis at least between the lower ones

37A. Spathe-blade broadly deltoid-ovate, the rachis of leaflets spirally curved on the apical part, the auricles almost wanting A. takedae

37B. Spathe-blade narrower, gradually tapering toward both ends from the middle, the auricles developed

38A. Auricles of the spathe very broad; Kanto to Oshima in Izu Provence A. limbatum

38B. Auricles of spathe narrow

39A. Spadix-appendage bulbously thickened at apex, smooth or rugose

40A. Spathe-blade elongate, nearly as long as the tubular part, spreading nearly at a right angle over the mouth; Kyushu A. mayebarae

40B. Spathe-blade always shorter than the tubular part, strongly declined at the tip over the mouth; eastern Honshu A. serratum

39B. Spadix-appendage slightly or scarcely thickened, smooth

41A. Tuber globose, not depressed; Isu Islands A. hachijoense

41B. Tuber depressed-globose; western Honshu A. japonicum