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32 University of California Publications in Botany Almeda: Systematics of the 18 Cauline internodes and upper foliar surfaces covered with shaggy, plumose trichomes; principal leaves ovate to ovate-elliptic, 7-9 plinerved abaxially, (1.3-)2.0-4.0 cm long; lower foliar surface covered with a mixture of plumose and sessile or stalked and stellate trichomes 15. M. pulchrum 18. Cauline internodes and upper foliar surfaces covered with distinctly barbellate (at least distally so) or smooth trichomes; principal leaves elliptic, elliptic-lanceolate, ovate-lanceolate, linear-oblong, or elliptic-ovate, 3-5-plinrtbrf snscislly, 2.0-2.5(-2.9) cm wide; lower foliar surface never covered with a mixture of plumose and sessile or stalked, stellate trichomes. 19. Sprawling or decumbent, diffusely branched subshrubs, or slender, erect, suffrutescent perennials; hypanthia covered with spreading, smooth trichomes and spreading, glandular trichomes. 20. Branchlets copiously hirsute; young branchlets held at an angle of 65-90°; principal leaves elliptic, elliptic-ovate, or ovate; mature hypanthia 7-9(-10) mm long; petals rounded to shallowly emarginate apically; seeds dark brown, smooth, vernicose, tightly cochleate, somewhat semicircular, laterally compressed without a pronounced gyration; Panama . . . . 16. M. trichophyllun 20. Branchlets sparsely hirtellous; young branchlets held at an angle of 45° or less; principal leaves ovate-lanceolate to linear-lanceolate; mature hypanthia (4-)5-6(-7) mm long; petals apiculate apically; seeds orange-brown, minutely foveolate with a dull luster, cochleate to arcuate, with conspicuous lateral gyration; Guatemala 17. M. tenellum 19. Erect, strictly to arcuately branched shrub; hypanthia covered with appressed, smooth or distinctly barbellate trichomes (often intermixed with spreading, glandular trichomes). 21. Distal internodes sparsely hirtellous, quadrangular to subquadrangular with strongly carinate to slightly winged expansions at the junction of adjacent stem faces; hypanthial trichomes smooth (sometimes intermixed with glandular trichomes); uppermost floral bracts 1.1-1.8 (-2.5) mm long; style (9-)10-15(-17) mm long 2. M. calcaratum 21. Distal internodes moderately to copiously hirsute, ± terete; hypanthial trichomes barbellate, often intermixed with spreading, glandular trichomes; uppermost floral bracts (l-)4-ll(-lS) mm long; style-5-11 mm long. 22. Mature hypanthia campanulate to cylindric; flowers solitary or paired (rarely disposed in dichasia); uppermost floral bracts elliptic, elliptic-lanceolate, or elliptic-ovate, 4-ll(-13) mm long 12. M. deppeanum 22. Mature hypanthia urceolate to suburceolate; flowers borne in once- to thrice-compound dichasia; uppermost floral bracts cordate, suborbicular, ovate, or spatulate, 1-6.5 mm long. 23. Principal leaves elliptic to elliptic-ovate (7-)9-2S(-28) mm long, (3-)4-ll(-13) mm wide; internodal trichomes usually less than 1 mm long; sepals linear-oblong to lance-deltoid, obtuse to rounded apically, 4-6 mm long; petals broadly elliptic to narrowly obovate, rounded to oblique apically, 12.5-19 mm long 18. M. compactum 23. Principal leaves lanceolate to elliptic-lanceolate, (1.4-)2-4(-8) cm long, (4-)6-15(-29) mm wide; internodal trichomes usually l-3(-5) mm long; sepals lance-triangular, acute apically, 3-5 mm long; petals ovobate, shallowly emarginate to retuse, rarely apiculate apically, 9-14 mm long 11. M. floribundum iaceous, entire, or with stout, distally barbel clasping, strongly decussate, held at right an (-40) mm wide at the broadest point (usually t glabrous, or more commonly with a single, lo tween the impressed primary nerves traversin present only along the foliar apex; lower leaf glabrous, or with trichomes comparable to th A 1. Monochaetum cordatum Almeda, sp. nov. (Fig. 6) Frutex erectus ad 3 m altus; rami glabri. Folia cordata, sessilia, Integra vel minute crenulata, glabra vel sparsim strigosa, (l.l-)2-6.7(-9) cm longa et (8-)ll-32(-40) mm lata, 7-9(-ll) nervata, nervorum pari exteriore inconspicuo. Inflorescentiae terminales, dichasiales; bracteis ovatis vel lanceolato-ovatis, 5-23 mm longis et 2-14 mm latis. Calycis lobi lanceolati, (4.5-)5-7 mm longi et 2-3 mm lati, persistentes. Petala rosea, obovata, 1.6-1.9 cmlongaet 1.4-1.7 cmlata. Staminum maiorum filamenta 6-9 mm longa, thecis6.5-9(-10) mm latis, appendicibus dorsalibus 4.5-5.5(-6.5) mm longis. Staminum minorum filamenta 8.5-10 mm longis, thecis 3.5-6 mm longis, appendicibus dorsalibus (2-)3-4 mm longis. Stylus 9-1S mm longus. Hypanthium (maturum) plerumque glabrum, cylindricum, 6-9 mm longum et S-4(-5) mm latum. Semina 0.5 mm longa, brunnea, minute foveolata, cochleata. Erect, laxly branched shrub 1 -3-m tall. Cauline internodes glabrous, those of the young shoots indistinctly quadrangular with two opposing flat to slightly concave faces, the remaining pair convex but becoming illdefined at the nodes and somewhat rounded with age. Nodal trichomes tufted, spreading, barbellate, less than 1 mm long. Older stems woody, reddish brown, the bark exfoliating. Principal leaves thick, subcori- H Fig. 6. Monochaetum cordatum. A, habit, X C, ovary and style (hypanthium removed), X 3; D panthium and calyx lobes, X 3; F, seeds, X 18; G Almeda 1330.) orw in Botany th shaggy, plumose trichomes; principal 12.0-4.0 cm long; lower foliar surface cov:llate trichomes 15. M. pulchrum distinctly barbellate (at least distally so) or olate, ovate-lanceolate, linear-oblong, or e; lower foliar surface never covered with omes. or slender, erect, suffrutescent perennials; md spreading, glandular trichomes. t an angle of 65-90°; principal leaves ellip10) mm long; petals rounded to shallowly licose, tightly cochleate, somewhat semiciration; Panama . . . . 16. M. trichophyllum I at an angle of 45° or less; principal leaves ithia (4-)5-6(-7) mm long; petals apiculate th a dull luster, cochleate to arcuate, with 17. M. tenellum :overed with appressed, smooth or distinctly ;, glandular trichomes). ,r to subquadrangular with strongly carinate adjacent stem faces; hypanthial trichomes trichomes); uppermost floral bracts 1.1-1.8 2. M. calcaratum e, ± terete; hypanthial trichomes barbellate, homes; uppermost floral bracts (l-)4-ll(-lS) Almeda: Systematics of the Genus Monochaetum (Melastomataceae) S3 iaceous, entire, or with stout, distally barbellate trichomes along the minutely crenulate margins, sessile, clasping, strongly decussate, held at right angles to the stems, cordate, (l.l-)2-6.7(-9) cm long, (8-)ll-32 (-40) mm wide at the broadest point (usually the basal third), acute apically; upper leaf surface dark green, glabrous, or more commonly with a single, longitudinal belt of appressed, distally roughened trichomes between the impressed primary nerves traversing the distal two thirds or half of the blade, or with trichomes present only along the foliar apex; lower leaf surface light green or deeply pigmented, obscurely punctate, glabrous, or with trichomes comparable to the upper surface but concentrated on and between the 9(-ll) flowers solitary or paired (rarely disposed in lliptic-lanceolate, or elliptic-ovate, 4-ll(-13) 12. M. deppeanum ; flowers borne in once- to thrice-compound >orbicular, ovate, or spatulate, 1-6.5 mm long. -)9-2S(-28) mm long, (5-)4-ll(-13) mm wide; m long; sepals linear-oblong to lance-deltoid, ;; petals broadly elliptic to narrowly obovate, ong 18. M. compactum eolate, (1.4-)2-4(-8) cm long, (4-)6-15(-29) mm ) mm long; sepals lance-triangular, acute api>wly emarginate to retuse, rarely apiculate api11. M. floribundum i Almeda, sp. nov. :ssilia, Integra vel minute crenulata, glabra vel mmlata, 7-9(-ll) nervata, nervorum pari exteribracteis ovatis vel lanceolato-ovatis, 5-23 mm nlongiet2-3mmlati, persistentes. Petala rosea, aiorum filamenta 6-9 mm longa, thecis 6.5-9(-10) 5. Staminum minorum filamenta 8.5-10 mm Iont mm longis. Stylus 9-13 mm longus. Hypanthium gum et S-4(-5) mm latum. Semina 0.5 mm longa, ies glabrous, those of the young shoots indistinctly aces, the remaining pair convex but becoming ill'odal trichomes tufted, spreading, barbellate, less : bark exfoliating. Principal leaves thick, subcori- Fig. 6. Monochaetum cordatum. A, habit, X 14; B,H, abaxial surface of representative leaves, X ca. 1; C, ovary and style (hypanthium removed), X 3; D,I abaxial surface of floral bracts, X SV£; E, mature hypamhium and calyx lobes, X3;F, seeds, X 18; G, petal, X 2 ^ . (A & F from Almeda 974A; B-E, G-I from Almeda 1}}0.) 34 University of California Publications in Botany elevated primary nerves; trichomes between primaries shorter and concentrated at the base of the blade. Primary nerves diverging from a common point at the base of the blade, the outermost pair depressed and usually evident only along the rounded base of the blade, becoming confluent with foliar margins distally. Inflorescence terminal, laxly branched, (2-)3-4 times compound dichasium. Floral bracts reduced upward, sessile, cordate to lance-ovate, glabrous above or beset with trichomes along the entire margins, glabrous below or with scattered trichomes restricted to the primary nerves; lowermost bracts 9-nerved, 1.1-2.S cm long, 6-12(-14) mm wide, uppermost bracts (5-)7-nerved, 5-ll(-14) mm long, (2-)S-5(-10) mm wide. Floral pedicels 7-19 mm long, glabrous, erect at anthesis but often becoming strongly cernuous in fruit. Hypanthium (at anthesis) narrowly campanulate, commonly dark burgundy in color, occasionally with scattered, appressed, distally roughened or barbellate trichomes (0.5-)l-2 mm long; hypanthial body glabrous with trichomes restricted to the external toral region at the base of the sepals. Hypanthium (at maturity) cylindrical, terete, or appearing obscurely 8-ribbed on drying, 6-9 mm long, 3-4(-5) mm wide. Sepals (on mature hypanthia) usually spreading, narrowly lanceolate, ciliate, glabrous, without or with a few trichomes basally, (4.5-)5-7 mm long, 2-3 mm wide at the base, persistent. Petals pink with darker pink or deep red venation pattern, obovate, entire, commonly tipped with a single trichome, 1.6-1.9 cm long, 1.4-1.7 cm wide. Antepetalous staminalfilaments 6-9 mm long; anthers deep red dorsally and suffused with yellow along the ventral surface of the anther thecae, 6.5-9(-10) mm long, 1-1.5 mm wide, the apical pore 0.5 mm or less in diameter; appendages yellow, but commonly white or translucent basally, clavate, 4.5-5.5(-6.5) mm long, 0.5 mm wide. Antesepalous staminal filaments 8.5-10 mm long; anthers yellow, 3.5-6 mm long, 1 mm or less wide, the apical pore 0.5 mm or less in diameter; appendages yellow, narrowly elliptic and often irregularly lobed or notched apically, (2-)3-4 mm long, 0.5-1 mm wide. Ovary (at maturity) oblong to subcylindric, setose apically. Style 9-13 mm long. Seeds 0.5 mm long, light to coppery brown, minutely foveolate, cochleate; n = 18. Type. — PANAMA. Chiriqui Province; 2-2.5 km E of Cerro Punta and 1 km E of Bajo Grande, elev. 2200 m, December 23, 1971, Almeda 9 Wilbur 9T4A (Holotype, DUKE; isotypes, BM, BR, F, G, GH, K, LL, MEXU, MICH, MO, NY, P, PMA, UC, US, W). Flowering. — November through February and only sporadically from March through July. Habitat and distribution. — Northern slopes and canyons adjoining Volcan Baru, Panama, and the northern foothills of the Cordillera de Talamanca E of Tapanti, Costa Rica. Restricted to roadbanks, pastu-elands, and steep, rocky slopes at elev. 1500-2500 m (fig. 7). Monochaetum cordatum, one of two species known only from Costa Rica and Panama, is a well-marked taxon unlikely to be confused with other members of the genus, It is readily recognized by its lax, dichotomously branched habit, sessile, prominently nerved, cordate leaves, glabrous hypanthia, and cauline internodes. Aside from local variations in foliar size, the species is uniform morphologically. Most populations examined in the course of this study consist of few individuals, so it is not surprising that M. cordatum was known from a single, fragmentary specimen prior to 1971. The distinctive vegetative features of this species make it difficult to propose any close relatives. It is for this reason that I have chosen to place it in a species group of its own, Trichome morphology supplies the only clue to a possible relationship between M. cotdatum and M. exaltatum. Both species share a trichome type which is smooth or gently ridged basally and roughened or distinctly barbellate distally (fig. 1 M, N, O). This trichome feature and the occurrence of natural interspecific hybridization (see discussion following) suggest a close relationship between these entities. Sympatry. —At its only known Costa Rican locality in the vicinity of Orosi, M. cordatum grows with M. macrantherum and M. neglectum without apparent hybridization. If gene exchange is possible between these species, it is limited by the small population size of each taxon and by the fact that none has been found in contiguous stands. In Panama, M. cordatum grows sympatrically with M. exaltatum and M.flonbundum. On one occasion I found it growing with single specimens of M. neglectun and M. trichophyllum in the mountains northwest of Boquete. Approximately 2.5-3.0 ications in Botany er and concentrated at the base of the blade. >f the blade, the outermost pair depressed and coming confluent with foliar margins distally. und dichasium. Floral bracts reduced upward, trichomes along the entire margins, glabrous nerves; lowermost bracts 9-nerved, 1.1-2.3 cm 11(-14) mm long, (2-)3-5(-10) mm wide. Floral i becoming strongly cernuous in fruit. Hypanburgundy in color, occasionally with scattered, -2 mm long; hypanthial body glabrous with trithe sepals. Hypanthium (at maturity) cylindrirrni long, S-4(-5) mm wide. Sepals (on mature glabrous, without or with a few trichomes basPetals pink with darker pink or deep red venae trichome, 1.6-1.9 cm long, 1.4-1.7 cm wide, red dorsally and suffused with yellow along the 1.5 mm wide, the apical pore 0.5 mm or less in lucent basally, clavate, 4.5-5.5(-6.5) mm long, long; anthers yellow, 3.5-6 mm long, 1 mm or lages yellow, narrowly elliptic and often irregu, wide. Ovary (at maturity) oblong to subcylinig, light to coppery brown, minutely foveolate, > Punta and 1 km E of Bajo Grande, elev. 2200 , DUKE; isotypes, BM, BR, F, G, GH, K, LL, adically from March through July. adjoining Volcan Baru, Panama, and the north, Costa Rica. Restricted to roadbanks, pastu-e)• known only from Costa Rica and Panused with other members of the genus, [y branched habit, sessile, prominently td cauline internodes. Aside from local m morphologically. Most populations • few individuals, so it is not surprising igmentary specimen prior to 1971. The ke it difficult to propose any close rela> place it in a species group of its own. , a possible relationship between M. cortrichome type which is smooth or gently .rbellate distally (fig. 1 M, N, O). This tl interspecific hybridization (see discustween these entities. locality in the vicinity of Orosi, M. corneglectum without apparent hybridizas species, it is limited by the small popuat none has been found in contiguous itrically with M. exaltatum and M. floriwith single specimens of M. neglectum west of Boquete. Approximately 2.5-3.0 36 University of California Publications in Botany Almeda: Systematic* km east of Cerro Punta, Panama, in a series of pasturelands extending less than half a 12 hectare, M. cordatum and M. exaltatum grow in an intermixed stand with morphological intermediates which are obvious products of interspecific hybridization. The 10 • • two species differ markedly in diagnostic morphological characters (figs. 6, 27). Quali-1 tative features of foliage, floral bracts, and hypanthia differ markedly, but scatter diaUJ gram portrayals also reveal differences in selected quantitative characters, displaying the striking intermediacy of putative hybrids (figs. 8, 9). When qualitative characters are codified (table 4) and summarized in the form of a hybrid index histogram, the re-' • M. exoltotum suiting pattern provides further insight into the morphological structure of the hybrid i swarm (fig. 10). A large proportion of the intermediates appear to be early generation I « Hybrids S5 hybrids. Individuals comprising index classes 8 and 14/15 possibly represent early j o M. cordatum backcross derivatives to M. cordatum and M. exaltatum respectively. The remaining assemblage of index classes may consist largely of F] and Fz hybrids, but assignment of this status is admittedly arbitrary on the basis of morphological criteria alone. 0 2 The relationship between pollen viability and morphological intermediacy follows LOWER no discernible pattern (appendix 6). Individuals with index values of 5 and 8 have re- \d fertility percentages of 65 and 86 Fig. 9. Scatter diagram represent show a gamut of variation. Some individuals in this class are sterile with pollen that is aberrant in both shape and size; others have pollen that appears normal and comparable to that of the putative parents. The majority of putative hybrids in index classes 11 through 15 appear normal and have viability percentages as high or higher 116 14 • ^. exaltatum e Hybrids • • • • • • •• • • •e • 0 00 0 0 « than parental values. The cyto nants in this hybrid swarm is u ity and morphological interme attributes are segregating and bility of many hybrid plants i gene flow back to one or both M. cordatum e 0 .0 0 0 0 50 o M. cordatum 45 0 tu oc. UJ X 10 < » CO 0 30 0 e a O o o o o UJ o: < 16 20 o o o o 12 O 20 LEAF 24 28 32 36 10 40 2 3 4 5 W I D T H (mm) Fig. 8. Scatter diagram representation of variation in Monochaetum cordatum, M. exaltatum, and putative hybrids. Fig. 10. Frequency distribution Monochae ications in Botany asturelands extending less than half a in an intermixed stand with morphots of interspecific hybridization. The jlogical characters (figs. 6, 27). Qualinthia differ markedly, but scatter diaed quantitative characters, displaying gs. 8, 9). When qualitative characters m of a hybrid index histogram, the remorphological structure of the hybrid nediates appear to be early generation 8 and 14/15 possibly represent early •xaltatum respectively. The remaining if F[ and Fz hybrids, but assignment of of morphological criteria alone, d morphological intermediacy follows s with index values of 5 and 8 have reively. Others with an index value of 10 this class are sterile with pollen that is pollen that appears normal and cornmajority of putative hybrids in index viability percentages as high or higher Almeda: Systematic* of the Genus Monochaetum (Melastomataceae) 37 12 i •• . E ~ 10 i Io z 8 bJ e o X I- o o o oo o • M. e x o l t o t u m z 2 > i » Hybrids o M. cordatum 3 4 LOWER FLORAL 6 8 BRACT 10 12 WIDTH (mm) Fig. 9. Scatter diagram representation of variation in Monochaetum exaltatum, M. cordatum, and putative hybrids. than parental values. The cytological basis for the reduced pollen viability of recombinants in this hybrid swarm is unknown. The lack of correlation between pollen viability and morphological intermediacy suggests that the genetic factors controlling these attributes are segregating and recombining independently. Given the high pollen viability of many hybrid plants in this swarm it is difficult to account for the minimal gene flow back to one or both parents. • M. exdltotum « Hybrids o M. cordatum 50 M. e x a l t a t u m 45 30 20 o o o z. 10 24 28 32 36 10 0 40 I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 HYBRID W I D T H (mm) INDEX VALUE Fig. 10. Frequency distribution of hybrid index values in the Panamanian population of Monochaetum cordatum and M. exaltatum. i in Monochaetum cordatum, M. exaltatum, hybrids. Almeda: Systematics of the ( Hybridization is presently occurrin major impact on the variation pattei exchange on the genetic and morphc turn should be of utmost interest, for logical events. 0 CD CO O CD O U -o c — O $3 u CD o T3 CD a CO CO 10 Representative specimens. — COSTA RICA. Ca (BM, DUKE, K, NY, US); Hwy #224 ca. 11.5 Wyatt 2170 (DUKE, US, W); Hwy #224 ca. 2 ca. 14-17 km E of Orosi, Luteyn 3946 (DUKE at Tapanti, Wilbur 9 Luteyn 18486 (DUKE Wilbur 7.5.50 (DUKE, US); Bajo Chorro trail (DUKE, F, GH, MICH, MO, LL, UC); withou Chorro trail from Paso de Respingo to Fila de )837C (DUKE); trailside in Quebrado Bajo 13126A (A, DUKE, F, MEXU, NY, P, PMA Cerro Punta, Wilbur et al. 1H94 (BR, CAS, Nubes, Wilbur & Almeda 17070 (DUKE); ra Cerro Picacho, Wilbur & Luteyn 19)87 (DU Putative hybrids between Monochaetum co E of Cerro Punta and 1 km E of Bajo Grande, ; .549 (DUKE, 6 plants), Almeda & Wilbur 1 Chorro trail, Luteyn 3837B (DUKE); edge o (DUKE, 7 plants); trailside in Quebrado Bajo 13126B (DUKE, 10 plants); ravine W of Las Wilbur a Luteyn 19380 (DUKE). CD E 'OQ E E «T > g o '5. I 11 0 0 r- O CO •D ^ aJ 0 •Bro *QJ £s "1 en CP g> co 4^ '-6 CD £ CD LU .- C -J O § CD u *- W ^ ! E 1 E co O- 2. Monochaetum calcaratum (DC I I = -C | § l l t/J o CD ^ CO ,y -o c *3~ ~ 00 O ~ai E 1 CO QJ CD a CD U C CD ~O — a ° E CO O 2 8 CD 4_ 14- "» CD -C O CD S" -5 Jf c w CD c C i5 ii 1 C CD Q;>, X -C +-J » CD CD Q_ cn C n 3 CD CD IE c ^c c a. a CD $ CO I Arthrostemma calcaratum DC. Prodr. 3:138 Type. — MEXICO: State not given, Cordillera PI; isotypes, BR1, GI [3 sheets], MOI, US!, Rhexia calcaratum (DC.) Schlecht. Linnaea Monochaetum enstferum Naudin, Ann. Sci. Type. — MEXICO: Oaxaca, Ghiesbreght 219 Monochaetum candolleanum Naudin, Ann. (nom illegit., ART. 63, I.C.B.N.) (Based o turn [A. P. de Candolle] Triana). Monochaetum oliganthum Naudin, Ann. Sc Type. —MEXICO: Oaxaca, Ghiesbreght s.n. Monochaetum naudinianum Neum. Rev. Ho Type. —MEXICO: exact locality unknown, breght (Holotype, not seen and perhaps no Monochaetum pringlei Rose, Contr. U.S. Na Type. —MEXICO: Morelos, Sierra de Tepoxt isotypes, Al, F!, Gl, GHI, MEXUI, MICHI, Monochaetum pringlei, f. latifolium Gleason Type. —MEXICO: Morelos, canyons above C type, Fl; isotypes, GHI [2 sheets], MICHI, M Monochaetum remotum Gleason, Amer.J.Bo Type. —MEXICO: Sinaloa, Sierra de Chaba Erect, openly branched, virgate shrub 1.5drangular, slightly carinate or winged where strongly canaliculate on drying. Branchlets to a £ "D a; Almeda: Systematics of the Genus Monochaetum (Melastomataceae) 39 Hybridization is presently occurring at only one locality and appears to have had no major impact on the variation patterns of either taxon. The long-term effect of gene exchange on the genetic and morphological integrity of M. cordatum and M. exaltatum should be of utmost interest, for it will depend on a number of unpredictable ecological events. Representative specimens. — COSTA RICA. Cartago: Hwy#224 ca. 20-24 km Eof Orosi, Almeda et al. 2)63 (BM, DUKE, K, NY, US); Hwy #224 ca. 11.5 km E of Orosi and just beyond Tapani!, Almeda, Flowers 9 Wyatt 2170 (DUKE, US, W); Hwy #224 ca. 20 km E of Orosi, Almeda et al. 2371 (DUKE, US); Hwy #224 ca. 14-17 km Eof Orosi, Luteyn 3946 (DUKE); steep banks of Rio Grande de Orosi ca. 12.9km SE of bridge atTapanti, Wilbur 9 Luteyn 18486 (DUKE). PANAMA. Chiriqui: 2-2.5 km E of Cerro Punta, Almeda Si Wilbur 1550 (DUKE, US); Bajo Chorro trail linking Boquete and Cerro Punta, Almeda 9 Wilbur 1598 (DUKE, F, GH, MICH, MO, LL, UC); without exact locality, Blum, Olson & Rasmussen 2421 (MO); Bajo Chorro trail from Paso de Respingo to Fila de Respingo, Luteyn 3832 (DUKE); Bajo Chorro trail, Luteyn 3837C (DUKE); trailside in Quebrado Bajo Grande ca. 2 mi E of Cerro Punta, Wilbur, Teeri & Foster D126A (A, DUKE, F, MEXU, NY, P, PMA, WIS); wooded slopes ca. 1 km N of Las Nubes and NW of Cerro Punta, Wilbur et al. 15194 (BR, CAS, DUKE, UC, US); trail through cloud forest in vicinity of Las Nubes, Wilbur 9 Almeda 17070 (DUKE); ravine W of Las Nubes ca. 5 km NW of Cerro Punta toward Cerro Picacho, Wilbur & Luteyn 19387 (DUKE). Putative hybrids between Monochaetum cordatum andM. exaltatum. —PANAMA. Chiriqui: ca. 2-2.5 km Eof Cerro Punta and 1 km Eof Bajo Grande, Almeda 9 Wilbur 975 (DUKE, 26 plants), Almeda 9 Wilbur J5«(DUKE, 6 plants), Almeda 9 Wilbur 1563 (DUKE, 6 plants), Almeda 9 Wilbur 974B (DUKE); Bajo Chorro trail, Luteyn 3837B (DUKE); edge of forested slope above Cerro Punta, Wilbur et al. 10907B (DUKE, 7 plants); trailside in Quebrado Bajo Grande ca. 2 mi E of Cerro Punta, Wilbur, Teeri 9 Foster 13126B (DUKE, 10 plants); ravine W of Las Nubes ca. 5 km NW of Cerro Punta toward Cerro Picacho, Wilbur » Luteyn 19380 (DUKE). E E 0) o •D E E CO CD o a o 2. Monochaetum calcaratum (DC.) Triana, Trans. Linn. Soc. Bot. 28:63. 1871 Arthrostemma calcaratum DC. Prodr. 3:138. 1828. Type. —MEXICO: State not given, Cordillera de Gutchillaque, October, 1827, Berlandier 997 (Holotype, PI; isotypes, BRI, G! [3 sheets], MOI, US!, Wl [3 sheets]). Rhexia calcaratum (DC.) Schlecht. Linnaea 13:431. 1839. Monochaetum ensiferum Naudin, Ann. Sci. Nat. III. 4:50. 1845. Type.-MEXICO: Oaxaca, Ghiesbreght 219 (Holotype, PI). Monochaetum candolleanum Naudin, Ann. Sci. Nat. Bot. III. 4:51. 1845. (nom illegit., ART. 63, I.C.B.N.) (Based on Arthrostemma calcaratum A. P. de Candolle, M. calcaratum [A. P. de Candolle] Triana). Monochaetum oliganthum Naudin, Ann. Sci. Nat. III. 14:159. 1850. Type.— MEXICO: Oaxaca, Ghiesbreght s.n. (Holotype, PI). Monochaetum naudinianum Neum. Rev. Hort. 1861:211. fig. 1861. Type. — MEXICO: exact locality unknown, described from cultivated material taken to Paris by Ghiesbreght (Holotype, not seen and perhaps nonexistent). Monochaetum pringlei Rose, Contr. U.S. Natl. Herb. 8:327. pi. LXXII. 1905. Type. - MEXICO: Morelos, Sierra de Tepoxtlan, 7500 ft., October 30, 1900, Pringle 8359 (Holotype, USI; isotypes, Al, F], Gl, GHI, MEXUI, MICHI, MOI, NYI, PI, UCI, VTI, Wl). Monochaetum pringlei, f. latifolium Gleason, Amer. J. Bot. 16:593. 1929. Type.— MEXICO: Morelos, canyons above Cuernavaca, 6500 ft., November 1, 1896, {Cringle 7352 (Holotype, Fl; isotypes, GHI [2 sheets], MICHI, MOI, USI [2 sheets], VTI). Monochaetum remotum Gleason, Amer.J.Bot. 16:593. 1929. Type. — MEXICO: Sinaloa, Sierra de Chabarria, Ortega 4055 (holotype, USI). Erect, openly branched, virgate shrub 1.5-4 m tall. Distal cauline internodes quadrangular or subquadrangular, slightly carinate or winged where adjacent faces intersect, at least two opposing faces becoming strongly canaliculate on drying. Branchlets totally glabrous, or hirtellous and sparsely covered with widely 1i b i