Tradescantia subg. Setcreasea (K.Schum. & Sydow) M.Pell., comb. et, Pellegrini, 2017

Pellegrini, Marco O. O., 2017, Morphological phylogeny of Tradescantia L. (Commelinaceae) sheds light on a new infrageneric classification for the genus and novelties on the systematics of subtribe Tradescantiinae, PhytoKeys 89, pp. 11-72: 35-38

publication ID

http://dx.doi.org/10.3897/phytokeys.89.20388

persistent identifier

http://treatment.plazi.org/id/229004D6-C2C3-5A60-87B7-D1B540AC569E

treatment provided by

PhytoKeys by Pensoft

scientific name

Tradescantia subg. Setcreasea (K.Schum. & Sydow) M.Pell., comb. et
status

stat. nov.

2.4. Tradescantia subg. Setcreasea (K.Schum. & Sydow) M.Pell., comb. et   stat. nov. Figs 6S View Figure 6 , 11 View Figure 11 , 13 View Figure 13

Tradescantia sect. Setcreasea   (K.Schum. & Sydow) D.R.Hunt, Kew Bull. 30(3): 448. 1975.

Neotreleasea   Rose, Contr. U.S. Natl. Herb. 8: 5. 1903, nom. superfluous.

Setcreasea   K.Schum. & Sydow, Just’s Bot. Jahresber. 27(1): 452. 1901.

Treleasea   Rose, Contr. U.S. Natl. Herb. 5: 207. 1899, nom. illeg., non Treleasia   Speg., Revista Fac. Agron. Univ. Nac. La Plata 2: 235. 1896. Type species. Tradescantia leiandra var. brevifolia   Torr. [≡ T. brevifolia   (Torr.) Rose]

Tradescantia sect. Separotheca   (Waterf.) D.R.Hunt, Kew Bull. 30(3): 454. 1975.

Separotheca   Waterf., Rhodora 61: 138. 1959, Syn. nov. Type species. Zebrina pumila   Greene (≡ T. pygmaea   D.R.Hunt).

Tradescantia sect. Tradescantia ser. Sillamontanae   D.R.Hunt, Kew Bull. 35(2): 440. 1980, Syn. nov. Type species. Tradescantia sillamontana   Matuda

Tradescantia sect. Tradescantia ser. Orchidophyllae   D.R.Hunt, Kew Bull. 35(2): 441. 1980, Syn. nov. Type species. Tradescantia orchidophylla   Rose & Hemsl.

Description.

Herbs geophytes, base definite, perennial, succulent, terrestrial or rupicolous. Roots thick, tuberous. Stems erect, sometimes prostrate with ascending apex, succulent, little branched to densely branched, rarely unbranched, rooting at the basal nodes, sometimes rooting at the distal ones when they touch the substrate. Leaves sessile; spirally-alternate, rarely distichously-alternate, evenly distributed along the stem or congested at the apex of the stems; sheaths closed; blades falcate and/or complicate, base symmetric, midvein conspicuous to inconspicuous, adaxially impressed, abaxially prominent, rounded, secondary veins conspicuous or inconspicuous. Synflorescences   terminal in the distal portion of the stems, composed of a solitary main florescence. Inflorescences (main florescences) consisting of a pedunculate double-cincinni fused back to back; inflorescence bract hyaline, tubular, inconspicuous; peduncle bracts absent; supernumerary bracts absent; cincinni bracts leaf-like, unequal to each other, saccate, conduplicate, free, overlapping each other; bracteoles expanded, imbricate or completely involving the cincinnus, linear-triangular to triangular or flabellate, hyaline. Flowers bisexual, actinomorphic, tubular, floral tube infundibuliform to hypocrateriform or campanulate; pedicel gibbous at apex, straight at anthesis and pre-anthesis, deflexed at post-anthesis; sepals equal, free, membranous, elliptic to broadly elliptic, not dorsally keeled, apex acute; petals sessile or clawed, equal, free to conate, blade elliptic to ovate to broadly ovate or rhomboid to broadly obovoid to obovoid, flat, base cuneate to obtuse, margin entire, apex acute to obtuse; stamens 6, arranged in two series, equal, filaments epipetalous, straight at anthesis and post-anthesis, glabrous to medially sparsely bearded with moniliform hairs, when present hairs shorter than the stamens, variously colored, anthers with connective quadrangular to rectangular, rarely rhomboid, yellow, anther sacs C-shaped, rarely ellipsoid, yellow, pollen yellow; ovary glabrous or pubescent, locules 2-ovulate, style straight at anthesis and post-anthesis, variously colored, cylindrical at base, cylindrical to obconical at the apex, stigma capitate to trilobate, pistil the same length as the stamens. Capsules subglobose to globose, light to medium brown when mature, glabrous or pubescent, loculicidal, 3-valved, sometimes apiculate due to persistent style base. Seeds exarillate, 1-2 per locule, ellipsoid to narrowly trigonal, ventrally flattened, not cleft towards the embryotega, testa scrobiculate to rugose, with ridges radiating from the embryotega, embryotega dorsal, conspicuous, with a prominent apicule.

Habitat, distribution and ecology.

Tradescantia subg. Setcreasea   is restricted to southern USA and Mexico (Fig. 11 View Figure 11 ). Its species are generally related to rocky outcrops and open dry areas. This is reflected in its species with tuberous roots and succulent vegetative organs.

Included species.

This subgenus is composed by 10 species: Tradescantia brevifolia   (Torr.) Rose, T. buckleyi   (I.M.Johnst.) D.R.Hunt, T. hirta   D.R.Hunt, T. leiandra   Torr., T. mirandae   Matuda, T. orchidophylla   Rose & Hemsl., T. pallida   (Rose) D.R.Hunt, T. pygmaea   D.R.Hunt, T. rozynskii   Matuda, and T. sillamontana   Matuda.

Comments.

Tradescantia subg. Setcreasea   comprises succulent plants with complicate leaves (Fig. 13A-F View Figure 13 ), tubular flowers (generally sympetalous and epipetalous; Fig13D, G-H, J-K) and filaments that range from glabrous to sparsely barbate with short moniliform hairs (Fig. 13H, J, K View Figure 13 ). This group was thoroughly studied and almost completely monographed by Hunt (1975), with only four of its currently accepted species not included in the key. Its morphology is considerably homogeneous, with species related with the commonly cultivated T. pallida   forming a species complex (Fig. 13A, E, G, K View Figure 13 ). Tradescantia sect. Tradescantia ser. Sillamontanae   was differentiated from T. sect. Setcreasea   by Hunt (1980) by the free petals and stamens (Fig. 13J View Figure 13 ), and densely lanate leaves (Fig. 13D, F View Figure 13 ); while T. sect. Tradescantia ser. Orchidophyllae   was differentiated by its free petals and stamens, and generally rotund leaves congested in a rosette. Nevertheless, these two groups share all the diagnostic features of T. subg. Setcreasea   (i.e. tubular flowers, pedicel the same length as the floral buds, hyaline sepals, fused and clawed petals, and epipetalous stamens), and there seems to be no good reason for treating them as separate groups inside T. subg. Setcreasea   . Furthermore, in the majority rule topology (Fig. 4A View Figure 4 ), these species are nested deep within T. subg. Setcreasea   and there is no way to recognize them as separate groups, without creating other non-monophyletic groups inside the subgenus. The peculiar-looking T. hirta   (Fig. 13C, H View Figure 13 ), was originally included by Hunt (1975) in his T. sect. Setcreasea   , and is morphologically very similar to T. mirandae   , differing primarily in leaf shape and androecium morphology. Furthermore, T. rozynskii   (Fig. 13D View Figure 13 ) and T. sillamontana   (Fig. 13F, I, J View Figure 13 ) can only be differentiated from the T. pallida   species complex due to their lanate indumentum covering the entire leaf-blade, and lack of clawed petals. Aside from that, these plants are morphologically very similar (see Fig. 13 View Figure 13 ). Tradescantia orchidophylla   is the morphologically most discrepant species in the subgenus, due to its wide leaf-blades and very long pedicels. Nonetheless, this morphology could be easily explained as a return to understory environments. Despite being placed by Hunt (1975) in a separate section, T. pygmaea   is undeniably similar to the species from the T. pallida   species complex. Besides the obvious stature difference (hence the species’ name; Fig. 13B View Figure 13 ), and the thicker tuberous roots, the only marking morphological difference between it and the species from the T. pallida   complex is the shape of the connectives and anthers sacs that are sagittate and elliptic, similar to the ones of T. mirandae   .

Kingdom

Plantae

Phylum

Tracheophyta

Class

Liliopsida

Order

Commelinales

Family

Commelinaceae

Genus

Tradescantia

Loc

Tradescantia subg. Setcreasea (K.Schum. & Sydow) M.Pell., comb. et

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Tradescantia sect. Setcreasea

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Neotreleasea

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Setcreasea

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Treleasea

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Treleasia

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Tradescantia leiandra var. brevifolia

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T. brevifolia

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Tradescantia sect. Separotheca

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Separotheca

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Zebrina pumila

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T. pygmaea

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Tradescantia sect. Tradescantia ser. Sillamontanae

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Tradescantia sillamontana

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Tradescantia sect. Tradescantia ser. Orchidophyllae

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Tradescantia orchidophylla

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