CAEDUACEAE. 



433 



2. Iva cheiranthifolia H.B.K. Nov. Gen. 4: 276. 1820. 



A much-branched shrub, 1-2 m. high, the slender twigs, the leaves and the 

 involucres densely and finely pubescent. Leaves opposite, narrowly oblong to 

 oblong-lanceolate or the lower obovate, 3-9 cm. long, obtuse or acute at the 

 apex, narrowed at the base, 3-nerved, the petioles 3-15 mm. long, the upper ones 

 much smaller ; peduncles shorter than the involucres ; heads nodding, numerous ; 

 involucj-e 3-4 mm. broad, its bracts 3-5, nearly orbicular; fertile flowers 3-5; 

 staminate flowers 5-8. 



Waste places and scrub-lands, Great Bahama, the Berry Islands, the Blminls, 

 Andros, New Providence and Eleuthera to Long Island : — Cuba. BcsH Iva. 



Family 6. OARDUACEAE Neck. 

 ThistLiE Family. 



Herbs, rarely shrubs (some tropical forms trees), with watery or res- 

 inous (rarely milky) sap, and opposite alternate or basal estipulate 

 leaves. Flowers perfect, jpistillate, or neutral, or sometimes monoecious 

 or dioecious, borne on a common receptacle, forming heads, subtended 

 by an involucre of few to many bracts arranged in one or more series. 

 Receptacle naked, or with chaffy scales subtending the flowers, smooth, 

 or variously pitted or honeycombed. Calyx-tube completely adnate to 

 the ovary, the limb (pappus) of bristles, awns, teeth, scales, or crown- 

 like, or eup-like, or wanting. Corolla tubular, usually 5-lobed or 5-oleft, 

 the lobes valvate, or that of the marginal flowers of the head expanded 

 into a ligule (ray) ; when the ray-flowers are absent the head is said to be 

 discoid ; when present, radiate ; the tubular flowers form the disk. Stamens 

 usually 5, borne on the corolla and alternate with its lobes, their anthers 

 united into a tube (syngenesious), often appendaged at the apes, some- 

 times sagittate or tailed at the base; pollen-grains globose, often rough or 

 prickly. Ovary 1-celled; ovule 1, anatropous; style of fertile flowers 2- 

 clef t ; stigmas marginal ; style of sterile flowers commonly undivided. Fruit 

 an achene. Seed erect; endosperm none; embryo straight; hypocotyl in- 

 ferior. About 800 genera and not less than 10,000 species, of wide geo- 

 graphic distribution. 



Perfect flowers with regular corollas. 



Stigmatic lines at the base of the stigma or below 

 the middle. 

 Stigmas filiform or subulate, hispidulous. 

 Stigmas more or less clavate, paplllose-puberu- 

 lent. 

 Stigmatic lines extending to the tip of the stigma 

 or to the appendages. 

 Anthers without elongated appendages at the tip. 

 Anther-sacs tailed at the base. 

 Anther-sacs not tailed at the base. 

 Receptacle naked. 



. Bracts of the InveLucre well imbricated. 

 Stigmas of the perfect flowers with 



terminal appendages. 

 Stigmas of the perfect flowers with 

 truncate, hairy or papillose tips. 

 Bracts of the Involucre little if at all 

 imbricated except when the broad 

 outer overlap the inner. 

 Receptacle chaffy ; bracts of the involucre 

 herbaceous, sometimes follaceous. ■ 

 Anthers with elongated, cartilaginous, mostly 

 connate appendages. , 



Perfect flowers, or all, with bilabiate corollas. 



Tribe I. Vbknonieae. 

 Tribe II. Bupatoeieae. 



Tribe IV. Inuleae. 



Tribe III. Astekeae. 

 Tribe VI. Helenieae. 



Tribe VII. Sbnecioneae. 



Tribe V. Heliantheab. 



Tribe VIII. Cinaeeae. 

 Tribe IX. Mdtisieae. 



