ASCLEPIADACEAE 745 



valvate in bud, with 5, sometimes 1 or many appendages (corona) adnate to the corolla-tube or to the stamens; stamens 5, the 

 filaments free or coherent in a tube, the anthers 2-locular, adnate to the stigma and forming a gynostegium, the pollen 

 coherent into waxy or granular masses (poilinia); ovary superior; carpels 2, with a marginal placenta; styles free, the stigma 



conical, sometimes discoid; fruit a follicle; seeds usually comose, the endosperm scanty. About 220 genera, with about 2,000 



species, in the Tropics and warmer regions, especially abundant in Africa. 



I A. Poilinia pendulous on caudicles. 

 2A. Corona short and depressed, much shorter than the gynostegium, the lobes alternate with the stamens; stigma long-beaked; 



cymes raccmelike 1 . MelapUxis 



2B. Corona as long as to longer than the gynostegium; cymes usually umbellikc 2. Cynanchiim 



IB. Poilinia erect on caudicles. 



3A. Poilinia small, discoid 3. Tylophora 



3B. Poilinia large, usually pyriform. 



4A. Leaves very thick, fleshy; inflorescence umbellate; corolla rotate 4. Hoya 



4B. Leaves membranous to coriaceous; corolla-tube prominent. 



5.\. Corolla campanulate 5. Marsdenia 



5B. Corolla salverform 6. Stephanolis 



1. METAPLEXIS R. Br. Gaga-imo Zoku 



Scandent herbs or subshrubs; leaves opposite, petiolate, cordate; cymes racemelike; flowers rather small; calyx 5-parted, with 

 5 glands inside at the base; corolla rotate-campanulate, deeply 5-lobed, the lobes narrow, contorted in bud, long-hairy inside; 

 corona annular, the lobes 5, alternate with the stamens and inserted on the stamen-tube; stamens coherent into a short tube, die 

 anthers with an incurved cordate membrane at the apex, the poilinia solitary in each anther-locule, ovoid-ellipsoidal, pendulous on 



the apex of a short caudicle; stigma enure or elongate to a long bifid beak; follicles rather thick; seeds comose. Few species, 



in e. Siberia and e. Asia. 



1. Metaplexis japonica (Thunb.) Makino. Pergidaria long as to slightly shorter than the pedicels, acuminate; corolla 

 japonica Thunb.; M. stauntonii Schult.; Urostelma chinense pale purple or white, about 1 cm. across, broadly campanulate, 

 Bunge; M. chinensis Decne. Gaga-imo. Sparsely white- deeply 5-lobed, die lobes lanceolate, recurved at tip, villous in- 

 pubescent scandent perennial herb, woody at base; leaves ovate- side; follicles puberulent or glabrous, 8-10 cm. long, about 2 

 cordate, 5-10 cm. long, 3-6 cm. wide, acute, abruptly cuspi- cm. across, broadly lanceolate; seeds flat, obovate, 6-8 mm. 

 date, cordate, glaucous beneath, the petiole shorter than the long, narrowly winged, with short, radiating striations on both 



blade; racemes 2-5 cm. long, pedunculate, the bracts linear, surfaces. Aug. Sunny slopes and thickets in hills and low 



shorter than the pedicel; calyx 4-5 mm. long, 5-parted nearly mountains; Hokkaido, Honshu, Shikoku, Kyushu. s. Ku- 



to the base, the segments deltoid-lanceolate, membranous, as riles, Korea, China, and Manchuria. 



2. CYNANCHUM L. Kamomezuru Zoku 



Erect or scandent herbs, rarely subshrubs; leaves usually opposite, petiolate or sessile; cymes umbellike, sometimes racemelike, 

 often branched, usually pedunculate; flowers small, white, greenish, or purplish; calyx 5-parted; corolla rotate or campanulate- 

 rotate, deeply 5-lobed, the lobes contorted, rarely valvate in bud, the corona inserted at base of the stamen-tube, truncate to 

 5-parted, as long as to longer than the gynostegium, often with secondary inner lobes inside; anthers with a membranous 

 appendage at apex, the poilinia solitary in each anther-locule, pendulous or sometimes horizontal on the caudicle; follicles thick 

 or slender; seeds comose. More than 100 species, in warm-temperate and subtropical regions. 



lA. Leaves ovate-cordate; rhizomes long-creeping; corona-lobes highly adnate on the ventral side to the gynostegium; membranous ap- 

 pendage of the anthers relatively large and prominent. 

 2A. Corolla-lobes slightly rcflexed; corona-lobes oblong or narrowly obovate, with an appendage inside much longer than the gynostegium. 



1 . C. caudatiim 

 2B. Corolla-lobes obliquely spreading; corona-lobes obovate-orbicular, slightly shorter than the gynostegium, without an appendage inside. 



2. C. wiljordii 

 IB. Leaves linear to narrowly deltoid-ovate, rarely cordate; rhizomes short; corona-lobes fleshy, as long as the gynostegium or much shorter; 

 membranous appendage of anthers small, %vhite at apex. 

 3A. Plant erect; leaves linear to narrowly lanceolate, acuminate at both ends, the petioles 1-3 mm. long; flowers yellow-brown. 



3. C. paniculatiim 

 3B. Plants erect, with broad leaves, or more or less scandent; flowers white, purple-brown, or sometimes yellowish. 

 ■lA. Leaves sessile, or short-pctiolate and clasping at base. 



5A. Leaves glaucescent, glabrous, sessile 4. C. ampUxicaiilc 



5B. Leaves yellow-green, crisped-hairy on both surfaces, the peUoles 3-4 mm. long 5. C. I^rameri 



4B. Leaves usually distinctly pcdolate, not clasping at base. 



6A. Leaves large, 3-15 cm. wide, of few pairs, more or less approximate toward the top of the stems or the stems more elongate 

 and becoming scandent with remote pairs of smaller leaves. 

 7A. Larger leaves ovate-orbicular to broadly elliptic, 7-15 cm. wide, rounded at base. 



8A. Corolla-lobes thinly white-pubescent inside; stems often elongate and scandent; follicles horizontally spreading to slighdy 



deflexed 7. C. grandijolitim 



8B. Corolla-lobes glabrous on both sides; stems erect; follicles ascending 8. C. magnificum 



