Murdannia Royle, Ill. Bot. Himal. Mts. 1: 403, pl. 95, f. 3. 1839.

Pellegrini, Marco Octavio de Oliveira, Faden, Robert B. & Almeida, Rafael Felipe de, 2016, Taxonomic revision of Neotropical Murdannia Royle (Commelinaceae), PhytoKeys 74, pp. 35-78 : 37-41

Murdannia Royle, Ill. Bot. Himal. Mts. 1: 403, pl. 95, f. 3. 1839.

Aphylax Salisb., Trans. Hort. Soc. London 1: 271. 1812, nom. nud. Type species. Aphylax spiralis (L.) Salisb. [≡ Murdannia spirata (L.) G. Brückn.].

Baoulia A.Chev., Bull. Soc. Bot. France 58 (8): 217. 1912. Type species. Baoulia tenuissima A.Chev. [≡ Murdannia tenuissima (A.Chev.) Brenan].

Dichaespermum Wight, Icon. Pl. Ind. Orient. 6: 31. 1853. Type species (designated here). Dichaespermum lanceolatum Wight [≡ Murdannia lanceolata (Wight) Kammathy].

Dilasia Raf., Fl. Tellur. 4: 122. 1838, nom. rej. Type species. Dilasia vaginata (L.) Raf. [≡ Murdannia vaginata (L.) G. Brückn.].

Ditelesia Raf., Fl. Tellur. 3: 69. 1837 nom. rej. Type species. Ditelesia nudiflora (L.) Raf. [≡ Murdannia nudiflora (L.) Brenan].

Phaeneilema G. Brückn., Bot. Jahrb. Syst. Beibl. 137: 63. 1926, nom. illeg. Type species. Phaeneilema sinicum (Ker Gawl.) G. Brückn. [= Murdannia simplex (Vahl) Brenan]

Prionostachys Hassk., Flora 49: 212. 1866. Type species (designated here). Prionostachys ensifolia Hassk. ex C.B. Clarke [= Murdannia gigantea (Vahl) G. Brückn.].

Streptylis Raf., Fl. Tellur. 4: 122. 1838, nom. rej. Type species. Streptylis bracteolata Raf. [= Murdannia spirata (L.) G. Brückn.].

Talipulia Raf., Fl. Tellur. 2: 17. 1837, nom. rej. Type species. Talipulia malabarica (L.) Raf. [= Murdannia nudiflora (L.) Brenan].

Type species.

Murdannia scapiflora (Roxb.) Royle [= Murdannia edulis (Stokes) Faden].

Description.

Herbs, perennial or annual, rhizomatous or not, with a definite or indefinite base, terrestrial to paludal to rooted emergent aquatics. Roots thin and fibrous or tuberous and fusiform. Rhizomes short to elongate. Stems trailing and ascending at the apex or erect, unbranched to densely branched, rooting in the rhizome and at the basal nodes, rarely at the distal ones when they touch the substrate. Leaves sessile; distichously or spirally-alternate, congested at the apex of the stem or evenly distributed along the stem; lamina flat to slightly falcate to falcate and/or conduplicate, base symmetrical, midvein inconspicuous to conspicuous, adaxially impressed or not, abaxially prominent or not, secondary veins conspicuous to inconspicuous. Synflorescence composed of a solitary main florescence or with 1-several coflorescences. Main florescences (inflorescences) terminal or axillary in the in the uppermost nodes, not perforating the leaf-sheaths; main florescence a thyrse, composed of 1-many cincinni; basal bract reduced to leaf-like; peduncle bracts (sterile bracts) absent; cincinni bracts persistent; cincinni, sessile to pedunculate, contracted to elongate, bracteoles flat or tubular, persistent or caducous. Flowers bisexual or male (the male ones with a reduced gynoecium), actinomorphic, zygomorphic or enantiostylous, chasmogamous, flat (not tubular); pedicels erect at anthesis and pre-anthesis, erect or deflexed at post-anthesis; sepals 3, equal, free, cucullate, membranous to chartaceous, dorsally not keeled, margins hyaline, accrescent and persistent in fruit; petals 3, sessile, equal to subequal, free, deliquescent, glabrous or with minute glandular hairs at base or medially bearded with moniliform hairs on the adaxial surface; stamens (2-)3, equal, antesepalous, filaments bent ca. 30° either to the left or to the right, free, glabrous or with minute glandular hairs or medially bearded with moniliform hairs, anthers dorsifixed, rimose, connective narrow, anther sacs parallel, elongate; staminodes 3-(4), antepetalous (if 4 staminodes are present, than 1 antesepalous to the lower sepal), filaments free, glabrous, minutely glandular-puberulous basally or medially bearded with moniliform hairs, antherodes dorsifixed, 3-lobed, indehiscent, connective expanded, golden yellow or mauve to purple; ovary sessile, bent ca. 30° on the opposite direction as the stamens, smooth, glabrous or glandular-puberulous, 3-locular, locules equal, locule 1-2-(6)-ovulate, style erect or gently curved at the apex, stigma truncate to capitate, papillate. Capsules loculicidal, 3-valved, apiculate due to persistent style base, smooth, glabrous or glandular-puberulous. Seeds exarillate, farinose, uniseriate, 1-2-(6) per locule, reniform to broadly ellipsoid or cuboid to polygonal, slightly to strongly cleft towards the embryotega, ventrally flattened or not, testa costate to slightly rugose or shallowly scrobiculate to scrobiculate to foveolate, with ridges radiating from the embryotega, appendaged or not, hilum elliptic or linear, embryotega lateral to semilateral or semidorsal.

Ecology and habitat.

As with most aquatic plants, Neotropical Murdannia are seldom collected throughout their distribution range. Despite that, they seem to be locally common or uncommon, depending on the species. They all seem to be intimately related to permanent and seasonal water bodies of drier domains and vegetation, such as flooded grasslands in the Cerrado, Chaco and Pantanal domains, or the white sand formations in the Amazon basin.

Morphological relationships among the Neotropical species and within the genus.

Murdannia is one of the six (i.e. Aneilema , Buforrestia , Commelina , Floscopa and Pollia ) out of 41 genera of Commelinaceae distributed in the Neotropics and Paleotropics. ( Faden 1998). Although few in number, the Neotropical species of Murdannia exhibit all the extremes in inflorescence morphology found in Murdannia as a whole. The terminal thyrse consisting of well-spaced whorls of cincinni, present in Murdannia gardneri and Murdannia paraguayensis , is elsewhere present only in the rare Central African Murdannia allardii (De Wild.) Brenan, and in the Asian species Murdannia divergens (C.B.Clarke) G. Brückn, and Murdannia juncoides (Wight) R.S.Rao & Kammathy ( Ancy 2014; Faden & Pellegrini pers. obs.). Glandular-pubescent sepals and pedicels, present in Murdannia burchellii (C.B.Clarke) M.Pell., comb. et stat. nov., Murdannia englesii , Murdannia gardneri , and Murdannia paraguayensis , are otherwise known only from the Asian species Murdannia medica (Lour.) D.Y.Hong (usually present) and Murdannia spectabilis (Kurz) Faden. Moniliform hairs on the upper surface of the petals, present in Murdannia schomburgkiana (Kunth) G. Brückn. and Murdannia semifoliata (C.B.Clarke) G. Brückn., are recorded only in the Asian and African Murdannia simplex (Vahl) Brenan. One-seeded capsule locules, which characterize Murdannia burchellii , Murdannia engelsii and Murdannia gardneri , are known only in the Asian/Malaysian Murdannia vaginata (L.) G. Brückn., and in the Indian Murdannia assamica Nampy & A.Ancy ( Ancy and Nampy 2014). Finally, characters present in one or more Neotropical species that are not recorded elsewhere in the genus, include: (1) inflorescences with whorls of 1-flowered cincinni (present in Murdannia paraguayensis ); (2) the presence of glandular hairs on the inflorescence axis, cincinnus peduncles and axes (present in Murdannia burchellii , Murdannia englesii , Murdannia gardneri , and Murdannia paraguayensis ); (3) petals with minute glandular hairs at base on the adaxial surface (present in Murdannia engelsii and Murdannia paraguayensis ); (4) the presence of glandular hairs on the filaments, ovaries and capsules (present in Murdannia engelsii and Murdannia paraguayensis ); (5) long moniliform hairs on the petals and not confined to the petal bases (present in Murdannia schomburgkiana and Murdannia semifoliata ); and (6) appendages on the seeds (present in Murdannia burchellii , Murdannia engelsii , Murdannia gardneri and Murdannia paraguayensis ).

Inflorescence architecture in Murdannia .

Brenan (1966) has shown a great diversity of inflorescence architecture in Murdannia , with variations in the position of the main florescence, total number of cincinni, number of nodes with cincinni, number of cincinni per node, and degree of development of each cincinnus. According to Panigo et al. (2011), the basic inflorescence pattern for Commelinaceae is a many-branched, pedunculate and terminal thyrse, with verticillate cincinni, each cincinnus multi-flowered. Based on Brenan (1966) and Panigo et al. (2011), we could also infer that the plesiomorphic inflorescence architecture for Murdannia would correspond to the basic inflorescence pattern for Commelinaceae . Brenan (1966) indicates that most of the variation in inflorescence architecture could be derived from this basic type, as exemplified by the Asian Murdannia divergens , by only three changes. On the other hand, Panigo et al. (2011) states that additional changes would be necessary to express all the known variation in the inflorescence morphology for Murdannia , as: (1) the production of coflorescences, in addition to the main florescence; (2) variation in the length of the peduncle and internodes of the main florescence; (3) variation in the number of cincinni per node; (4) variation in the arrangement of cincinni on each node of the main florescence; (5) variation in the length of the cincinnus peduncle; and (6) variation in the total flower number per cincinnus. These changes can occur separately or in different combinations. In the most extreme cases, the inflorescences are mainly axillary, each being fascicle-like, and composed of a few 1-flowered cincinni.

If we were to consider this stepwise change a possible evolutionary sequence within Murdannia , then the South American species with the most plesiomorphic inflorescence type would be Murdannia gardneri . By its reduced number of cincinni per node and change in their arrangement, the inflorescence of Murdannia burchellii could be morphologically derived from Murdannia gardneri . Murdannia paraguayensis , shares the numerous verticillate cincinni of Murdannia gardneri , but each cincinnus is reduced to a single flower. Murdannia engelsii has terminal or terminal and axillary inflorescences, that are reduced to single cincinni, but the cincinnus is 2-several-flowered. The most reduced inflorescences, and perhaps the ones that accumulated the greatest number of stepwise changes, can be observed in Murdannia schomburgkiana and Murdannia semifoliata , in which most inflorescences are fascicle-like, axillary in the distal leaves, and with all cincinni 1-flowered. Species with similarly reduced inflorescences are numerous in Asia [e.g. Murdannia blumei (Hassk.) Brenan, Murdannia crocea (Griff.) Faden, Murdannia keisak (Hassk.) Hand.-Mazz., Murdannia lanuginosa (Wall. ex C.B.Clarke) G. Brückn., Murdannia pauciflora (Wight) G. Brückn., Murdannia triquetra (Wall. ex C.B.Clarke) G. Brückn., and Murdannia versicolor (Dalzell) G. Brückn.], and represented in Africa by Murdannia axillaris Brenan ( Faden 2012; Ancy 2014). Nonetheless, some of them show characters not present in any of the Neotropical species, such as annual habit, biseriate seeds and yellow to orange flowers. Thus, in the absence of a well sampled molecular phylogeny it would be impossible to state whether the Neotropical species represent one or several distinct lineages in Murdannia .

Key to the native and invasive species of Murdannia in the Neotropics

1	Inflorescences composed of 2-several verticillate or alternate to subopposite cincinni, rarely composed of a solitary cincinnus, bracteoles persistent; flowers enantiostylous, sepals with glandular hairs or with a mixture of glandular and eglandular hairs, androecium glabrous or with minute glandular hairs; seeds with a ventri-lateral appendage	2
-	Inflorescences composed of a solitary cincinnus or fascicle-like, bracteoles caducous; flowers non-enantiostylous, sepals glabrous, androecium medially bearded with moniliform hairs; seeds without a ventri-lateral appendage	5
2	Bracteoles cup-shaped; pedicels erect at post-anthesis and in fruit; petals glabrous, filaments, ovaries and capsules glabrous; hilum in a deep depression	3
-	Bracteoles flat; pedicels deflexed at post-anthesis and in fruit; petals with minute glandular hairs at base on the adaxial surface, filaments, ovaries and capsules with glandular hairs; hilum in a shallow depression	4
3	Cincinni alternate, rarely subopposite, sinuate; plants generally delicate; stems prostrate, thin, densely branched at the base; leaves chartaceous, linear to linear-oblong; main axis of inflorescence with sparse eglandular and glandular hairs; cincinnus bracts with caudate apex; seeds densely farinose, the testa costate to slightly rugose	Murdannia burchellii (C.B.Clarke) M.Pell. (Fig. 1 )
-	Cincinni verticillate, straight; plants generally robust; stems ascending to erect, succulent, little branched at base to unbranched; leaves succulent, linear-lanceolate to lanceolate; main axis of inflorescence with dense glandular and sparse eglandular hairs; cincinnus bracts with acuminate apex; seeds farinose, the testa scrobiculate to foveolate	Murdannia gardneri (C.B.Clarke) G. Brückn. (Figs 3 - 4 )
4	Inflorescence reduced to a solitary cincinnus (but sometimes several clustered in a synflorescence near towards the shoot apex), peduncles with a mixture of eglandular (scabrid) and glandular to densely glandular hairs, cincinni 2-7-flowered; plants without a definite base; leaves distichously-alternate; flowers buds ovoid; capsules broadly ovoid to broadly ellipsoid, locules 1-seeded	Murdannia engelsii M.Pell. & Faden (Fig. 2 )
-	Inflorescence a terminal thyrse composed of several whorls of 1-flowered cincinni, peduncles with glandular to densely glandular hairs, cincinni 1-flowered; plants with a definite base; leaves spirally-alternate; flower buds ellipsoid to narrowly ellipsoid; capsules oblongoid to broadly oblongoid, locules 2-seeded	Murdannia paraguayensis (C.B.Clarke ex Chodat) G. Brückn. (Fig. 6 )
5	Leaves distichously-alternate; inflorescences long-pedunculate, exerted from the leaf-sheaths, cincinni 2-12-flowered, pendent; flowers zygomorphic, stamens 2, staminodes 4 (1 staminode antesepalous, sometimes lacking the antherode), antherodes white to cream; capsules ovoid to subglobose	Murdannia nudiflora (L.) Brenan (Fig. 5 )
-	Leaves spirally-alternate; inflorescences sessile, enclosed by the leaf-sheaths; cincinni 1-flowered, erect; flowers actinomorphic, stamens 3, staminodes 3, antherodes yellow (flowers uncertain in Murdannia aff. triquetra ); capsules oblongoid to ellipsoid	6
6	Annuals without a definite base; roots thin; stems trailing, apex ascending, densely branched; petals glabrous; capsules with 3-seeded locules; seeds transversely ellipsoid	Murdannia aff. triquetra (Wall. ex C.B.Clarke) G. Brückn. (Fig. 9 )
-	Perennials with a definite base; roots tuberous; stems erect (only the short rhizome prostrate), unbranched; petals medially bearded with moniliform hairs on the adaxial surface; capsules with 6-seeded locules; seeds cuboid to polygonal	7
7	Leaf-blades margins glabrous throughout, inflorescences-bearing leaves with expanded blades (2.2-13.6 cm long); anthers brown	Murdannia schomburgkiana (Kunth) G. Brückn. (Fig. 7 )
-	Leaf-blades margins ciliate at least at base, inflorescences-bearing leaves reduced to bladeless sheaths or with much reduced blades (0.2-1.8 cm long); anthers purple	Murdannia semifoliata (C.B.Clarke) G. Brückn. (Fig. 8 )

Figures

Figure 1. Murdannia burchellii (C. B. Clarke) M. Pell. Lectotype of Aneilema gardneri var. burchellii (K barcode K 000363240). Photograph courtesy of Royal Botanic Gardens, Kew, London.

Figure 2. Murdannia engelsii M. Pell. & Faden. A Sandy banks of rio Teles Pires, white arrow showing a subpopulation of Murdannia engelsii B detail of the stem, showing the conduplicate and falcate leaves, with amplexicaul bases C detail of the inflorescence, showing the deflexed pedicels at post-anthesis D side view of a male flower, showing the short and bent style. E front view of a bisexual flower, showing the long curved style F detail of a young fruit, showing the pedicel and sepals with glandular hairs, gently curved style and capitate stigma G-J seeds: G dorsal view of a seed, showing the scrobiculate and cleft testa, and the semilateral embryotega H ventral view of the same seed, showing the ventral furrows and tan appendage surrounding the hilum I dorsal view of another seed, showing the shallowly scrobiculate and slightly cleft testa, and the semidorsal embryotega J ventral view of the same seed, with the appendage removed, showing the linear hilum in a shallow depression. K, dorsal view of a seed, showing the smooth testa. Photographs A-F by M. E. Engels, G-J by R. F. Almeida.

Figure 3. Murdannia gardneri (Seub.) G. Brueckn. A Inflorescence, showing the verticillate cincinni and open lilac flowers B detail of the inflorescence, showing the ascending and straight cincinni C flooded grassland in the state of Minas Gerais. Photographs A-B by W. Milliken, C by I. L. M. Resende.

Figure 4. Murdannia gardneri (Seub.) G. Brueckn. Isolectotype of Aneilema gardneri (P barcode P 02088022). Photograph courtesy of the Museum National d'Histoire Naturelle, Paris.

Figure 5. Murdannia nudiflora (L.) Brenan. A Habit B detail of a stem, showing the apical and long-pedunculate inflorescence C front view of a bisexual flower. Photograph A, C by W. Vargas and B by M. E. Engels.

Figure 6. Murdannia paraguayensis (C. B. Clarke) G. Brueckn. A Detail of a flowering shoot, showing the succulent stem, succulent, canaliculate and falcate leaves, and an inflorescence with lilac flowers B Detail of the apex of a flowering shoot, showing a terminal inflorescence with white flowers, and pedicels deflexed post-anthesis C Inflorescence showing the 1 - flowered verticillate cincinni and open mauve flowers D Side view of a male flower, showing the sepals with glandular hairs E flooded grassland in Sidrolandia, Mato Grosso do Sul. Photograph A by I. L. M. Resende, B, E by S. N. Moreira and C-D by V. C. Souza.

Figure 7. Murdannia schomburgkiana (Kunth) G. Brueckn. Isolectotype of Aneilema schomburgkianum (P barcode P 02088026). Photograph courtesy of the Museum National d'Histoire Naturelle, Paris.

Figure 8. Murdannia semifoliata (C. B. Clarke) G. Brueckn. Lectotype of Aneilema semifoliatum (BM barcode BM 000938202). Photograph courtesy of The Natural History Museum of London.

Figure 9. Murdannia aff. triquetrum (Wall. ex C. B. Clarke) G. Brueckn., from Esteros de Arauca, Colombia. A Detail of a stem, showing an apical fruit B detail of an internode, showing a side view of a male flower. Photographs by M. Fernandez.