20. Ptilininium Raf. Mock Bishop's-weed 



Plants slender, erect, caulescent, branching, herbaceous, annual, from a fascicle 

 of fibrous roots; leaves pinnately decompound with filiform ultimate divisions or 

 the leaves reduced to fistulose sheathing petioles; inflorescence of compound 

 umbels, the peduncles terminal and axillary; involucre of entire or pinnatifid bracts; 

 involucel of entire bractlets; rays few to numerous, spreading-ascending to spread- 

 ing, the pedicels spreading; flowers white, rarely pink, the calyx teeth small to 

 prominent, the stylopodium conic; carpophore bifid at the apex or cleft to the 

 middle: fruit ovoid to suborbicular, compressed laterally, the dorsal ribs filiform, 

 rounded or acute, the lateral ribs small to corky-winged, forming a band around 

 the fruit; oil tubes solitary in the intervals and 2 on the commissure, the seed face 

 plane. 



A genus of five species of southeastern and south-central United States. 



1. Leaf segments crowded, appearing verticillate; styles 1.5-3 mm. long; plant 

 robust, 8-15 dm. high 2. P. costatum. 



1. Leaf segments not crowded; styles 0.2-1.5 mm. long; plants 2-8 dm. high (2) 



2(1). Leaf segments usually 3 at a node on the rachis; bracts usually 3-cleft; styles 

 0.2-0.5 mm. long, not strongly recurved 1. P. capillaceum. 



2. Leaf segments usually 2 at a node on the rachis; bracts usually entire; styles 



0.5-1.5 mm. long, strongly recurved 3. P. Nuttallii. 



1. Ptilimnium capillaceum (Michx.) Raf. Fig. 590. 



Plant 1-8.5 dm. high; leaves verticillate at the nodes, polymorphic in submerged 

 forms, broadly oblong, to 13 cm. long and 4 cm. wide, pinnately decompound, the 

 segments usually filiform, 3 at a node on the rachis; peduncles 2.5-10.5 cm. long, 

 exceeding the leaves; involucre of several pinnately cleft or rarely entire bracts 

 about one half as long as the rays; involucel of filiform bractlets shorter than the 

 pedicels; rays 4 to 20, spreading, subequal, 1-3.5 cm. long; pedicels 5 to 20, 3-12 

 (usually 4-6) mm. long; calyx teeth small, persistent; styles 0.2-0.5 mm. long, not 

 strongly recurved; fruit broadly ovoid, 1.5-3 mm. long, 1.5-2 mm. broad, the 

 lateral ribs conspicuous. 



In wet places in Okla. (Pushmataha and McCurtain cos.) and the e. half of Tex., 

 May-Aug.; from Mass., s. to Fla., w. to Mo., Kan. and Tex. 



2. PHlimnium costatiim (Ell.) Raf. Fig. 591. 



Plant 8-15 dm. high; leaves oblong, to 14 cm. long and 7 cm. wide, pinnately 

 decompound, the ultimate divisions filiform, crowded, appearing verticillate; pedun- 

 cles 7-14 cm. long, exceeding the leaves; involucre of very short usually entire 

 bracts; involucel of usually entire bractlets shorter than the pedicels; rays about 20. 

 spreading, subequal, 1.5-4 cm. long; pedicels 15 to 20, spreading, 4-5 mm. long; 

 calyx teeth conspicuous, deltoid, acute to subacuminate, persistent; styles 1.5-3 

 mm. long; fruit ovoid, 2-4 mm. long, 2-3 mm. broad. 



In swamps, boggy areas, savannahs and edge of moist woods in the e. half of 

 Tex.. June-Oct.; from N.C. to Ga., w. to Mo. and Tex. 



Plants described as P. texense Coult. & Rose, formerly referred to P. costatum 

 by Mathias and Constance are considered by Easterly (Brittonia 9:144. 1957) to 

 be of possible hybrid origin, combining the fruit characteristics of P. Nuttallii with 

 the vegetative characteristics of P. capillaceum. The center of distribution appar- 

 ently is in Robertson County and the taxon is found through a large area of 

 eastern Texas in acid bogs and marsh land, flowering July to August. 



3. Ptilimnium NuttaUii (DC.) Britt. 



Plant 3-6 dm. high; leaves oblong, to 9 cm. long and 4 cm. wide, pinnately 

 decompound, the ultimate divisions filiform, usually 2 at a node on the rachis; 



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