Gentiana (Pringle, 1978)

Favre, Adrien, Pringle, James S., Heckenhauer, Jacqueline, Kozuharova, Ekaterina, Gao, Qingbo, Lemmon, Emily Moriarty, Lemmon, Alan R., Sun, Hang, Tkach, Natalia, Gebauer, Sebastian, Sun, Shan-Shan & Fu, Peng-Cheng, 2020, Phylogenetic relationships and sectional delineation within Gentiana (Gentianaceae), TAXON 69 (6), pp. 1221-1238 : 1232-1233

New determination key to the sections of Gentiana . —

This determination key was modified from Ho & Liu (1990). As shown in Fig. 3 , sections with identical trait values do not necessarily cluster together. Many of these diagnostic traits may have evolved several times, and some reversals are likely to have occurred. In the course of determination, Fig. 3 is designed to allow a quick pre-selection of potentially relevant sections.

1. Calyx hyaline, completely and closely enveloped by the uppermost pair of widely obovate leaves; stigma lobes orbicular, initially connivant and forming a discoid or funnelform structure, later diverging ............................ sect. Phyllocalyx

1. Calyx firmer in texture, at least partially extending above the involucral leaves, or involucre missing/absent; stigma lobes various...................................................................2

2. Intracalycular membrane absent, the calyx lobes inserted at the summit of the calyx tube; mostly annuals or other short-lived monocarpic (usually ± erect), or less often perennials (erect, decumbent, or procumbent); plants small, without a caudex; plants with stem length usually <20 cm, rarely to 30 cm; flowers most often solitary, in some species in few- or rarely several- to many-flowered dichasia; free portions of corolla plicae usually>0.5× as long as lobes, rarely (in G. prainii Burkhill ) minute ........ ....................................................... sect. Chondrophyllae

2. Intracalycular membrane present, the calyx lobes inserted slightly below the apex of the calyx tube; annuals or perennials with or without a caudex; plants diverse in size and habit but often> 20 cm; inflorescences diverse; free portions of corolla plicae diverse in size or (in G. lutea L.) absent..............................................................................3

3. Perennials with monopodial branching, i.e., with the primary stem or stems of the current year terminating in a persistent vegetative rosette and the flowering stems radiating out from axils of the primary stem below the central rosette; basal and lower cauline leaves well developed and persistent at anthesis.......................................................4

3. Perennials or annuals, if perennial then with sympodial branching, i.e., with the primary stem or stems of the current year arising directly from the rhizome and terminating in an inflorescence, and stems still vegetative at flowering time, none or, if present, radiating out from around the central flowering stem; basal leaves various......................... 6

4. Caudex succulent, with a sheath-like covering of fibrous, brown to blackish remains of old leaf bases; basal leaves usually much larger than cauline leaves, often narrow and strap-shaped, in other species wider and ± elliptic, the largest leaves generally> 3 cm long and in most species> 6 cm; roots usually contiguous and twisted into a stout, cylindrical structure; seed coat finely reticulate .................... ......................................................................... sect. Cruciata

4. Caudex neither succulent nor densely covered with fibrous remains of old leaf bases; basal/cauline leaf proportions various, but largest leaves usually <3 cm long, in a few species to 4 cm; roots not contiguous and twisted; seed coat alveolate, with hexagonal pits in a honeycomb-like pattern ............................................................................... 5

5. Flowers generally terminal and solitary, rarely 2 or 3; terminal rosette leaves usually similar in size to the cauline leaves; cauline leaves closely spaced (mostly longer than internodes), usually linear to narrowly lanceolate or narrowly elliptic; corolla plicae symmetrical..... sect. Kudoa

5. Flowers usually in a terminal cluster of 2 or more and sometimes also axillary (but often solitary in G. duclouxii Franch. , and occasionally solitary in G. davidii Franch. ); terminal rosette leaves usually distinctly larger than the cauline leaves; cauline leaves elliptic or oblanceolate to obovate; corolla plicae usually slightly to strongly asymmetrical and oblique, in a few species symmetrical or nearly so .............................................. sect. Monopodiae

6. Stoloniferous perennials; stigma lobes orbicular, initially connivent and forming a discoid or funnelform structure, later diverging................................................................7

6. Stoloniferous (sect. Isomeria ) or non-stoloniferous, annuals or perennials; stigma lobes ± oblong or linear, erect in bud, diverging and spreading at anthesis, not expanded and forming a discoid or funnelform structure...................8

7. Corolla salverform or nearly so, with a cylindrical to narrowly obconic tube and lobes ± abruptly spreading; free portions of plicae small, much shorter and narrower than lobes, usually symmetrically divided into two triangular teeth ..................................................... sect. Calathianae

7. Corolla urceolate, campanulate, or widely obconical, with the tube expanding distally and lobes ± gradually spreading; free portions of plicae about as wide at the base as the lobes and variously subentire to erose-undulate at the summit .................................... sect. Ciminalis

8. Stoloniferous; leaves with whitish cartilaginous margins; flowers often solitary, but occasionally in clusters of 2 to 4 ............................................................ sect. Isomeria

8. Non-stoloniferous; leaves entire, without whitish cartilaginous margins; flowers solitary or variously clustered...............................................................................9

9. Flowers tetramerous; calyx lobes with prominent keels decurrent on the tube; style filiform, about as long as or longer than the ovary............................. sect. Tetramerae

9. Flowers generally 5-merous (occasionally to 7-merous in sect. Gentiana ); calyx lobes usually not keeled (keeled in a few species in sect. Pneumonanthe ); style short and stout, often not sharply differentiated from the ovary, or, if style filiform (in some species in sect. Microsperma ) then calyx not keeled....................................................10

10. Perennials; rhizome succulent; base of stems sheathed with brown to blackish remains of old leaf bases; basal and lower cauline leaves persistent at flowering time, larger than the upper cauline leaves; seed coats with membranous lamellae forming spongy hexagonal pits ....... sect. Frigida

10. Annuals or perennials; rhizome non-succulent; base of stems sheathless, without remains of old leaf bases; basal leaves persistent or absent at flowering time; seed coat alveolate or reticulate...................................................11 11. Annuals; stems <30 cm; seed coat alveolate, with a honeycomb-like pattern.................................. sect. Microsperma

11. Perennials; stems generally> 30 cm; seed coat reticulate................................................................................12

12. Lateral rosettes generally present; flowers numerous in dense terminal and axillary clusters; basal leaves large and persistent at flowering time; corolla plicae minute, often appearing lateral on the lobes, or (in G. lutea ) absent...................................................... sect. Gentiana

12. Lateral rosettes generally absent; inflorescences various; basal leaves generally absent at flowering time and stems generally with the lowest leaves ± scale-like, the leaves gradually larger at the upper nodes (basal and lower cauline leaves relatively large and persistent only in G. newberryi A.Gray s.l. and G. setigera A.Gray); corolla plicae well developed, the apex generally extending in free portions between the lobes (forming a ± truncate gap between the lobes only in G. sceptrum Griseb. )................... ......................................................... sect. Pneumonanthe

Figures

Fig. 3. Distribution of morphological traits relevant for the identification of sections in Gentiana, in the light of phylogenetic relationships among these sections. The phylogenetic tree is identical to the one shown in Fig. 1.