What’s a dichotomous key?
Help
Group 7: Herbaceous angiosperms with superior ovaries and zygomorphic flowers
See list of 23 families in this group-
-
2b. Plants not insectivorous; flowers with 4–6 stamens; placentation axile or parietal
-
3a. Stamens numerous; both the calyx and corolla spurred, the 2 upper petals prolonged backward into a spur that extends into the upper, spurred sepal; leaf blades palmately divided (in part)
-
3b. Stamens 4–12; either the calyx or corolla spurred, but not both (hypanthium with a spur in Cuphea); leaf blades not palmately divided (palmately lobed in some Viola)
-
4a. Corolla 6-merous; androecium with 11 or 12 stamens; flowers perigynous (in part)
-
4b. Corolla 3- to 5-merous; androecium with 4–8 stamens; flowers hypogynous
-
5a. Androecium with 8 stamens; leaf blades with peltate petioles
-
5b. Androecium with 4–6 stamens; leaf blades with basifixed petioles
-
6a. Calyx spurred (note: the calyx is, in part, petaloid and can be misinterpreted as part of the corolla) [Fig. 478]; capsule dehiscing elastically; gynoecium with 5 carpels
-
6b. Corolla spurred [Figs. 757,759]; capsule not dehiscing elastically; gynoecium with 2 or 3 carpels
-
7a. Calyx of 2, often caducous, sepals; flowers with 6 stamens; leaf blades decompound (in part)
-
7b. Calyx of 5 sepals; flowers with 4 or 5 stamens; leaf blades variously simple to lobed, but not many times dissected
-
-
-
-
-
-
1b. Perianth lacking a nectary spur
-
9a. Upper sepal much larger than the other 4, petaloid, arched, forming a helmet-shaped structure that conceals the 2 petals; leaf blades palmately divided, with pinnately lobed segments (in part)
-
9b. Calyx without a single, larger, helmet-shaped sepal, sepaloid or petaloid; petals 3–8, not concealed by the calyx; leaf blades otherwise
-
10a. Calyx with 2 sepals; androecium of 3 stamens; fruit a capsule with 1–3 seeds (in part)
-
10b. Calyx with 4–6 sepals; androecium of 2–25 stamens, but not 3; fruit a capsule, silique, legume, schizocarp, or achene
-
11a. Fruit a legume or schizocarp; gynoecium with 1 carpel; stamens monadelphous or diadelphous (distinct in Baptisia, Chamaecrista, Senna, and Thermopsis); lower 2 petals fused into a keel (only the banner petal present in Amorpha, lower 2 petals distinct in Chamaecrista and Senna) [Figs. 638,642,657] (in part)
-
11b. Fruit a capsule, silique, schizocarp, or achene; gynoecium with 2 or more carpels; stamens distinct (monadelphous in Polygala); lower 2 petals variously distinct or connate
-
12a. Corolla apopetalous; androecium of 6–27 stamens
-
13a. Leaf blades pinnately compound with 7–13 leaflets, punctate with transparent glands; gynoecium with 5 carpels (in part)
-
13b. Leaf blades entire to lobed or compound, when pinnately compound with only 3 leaflets, not glandular-punctate; gynoecium with 2–4 carpels
-
14a. Petals 4–6, the apical portion bearing a fringe of linear to oblanceolate segments that are ± equal to the length of the petal [Fig. 822]; gynoecium with 3 or 4 carpels; fruit a capsule; leaf blades entire to pinnately lobed
-
14b. Petals 4, the apical portion lacking a fringe; gynoecium with 2 carpels; fruit a silique; leaf blades palmately compound or pinnately trifoliate (in part)
-
-
-
12b. Corolla gamopetalous; androecium of 2–8 stamens
-
15b. Calyx composed mostly of 4 or 5 sepaloid sepals, but not as in the Polygalaceae; flowers with 2–5 distinct stamens
-
16a. Carpels 2, each carpel lobed, often evidently so, therefore, the gynoecium appearing to be composed of 4 carpels, separating at maturity into 4 half-carpellate segments; fruit a schizocarp
-
17b. Inflorescence not appearing as a coiled raceme [Figs. 695,700,927]; leaves opposite; stems usually quadrangular
-
18b. Style usually with an inconspicuous stigma; carpels usually evidently lobed; inflorescence mixed (i.e., thyrsoid), with cymose lateral branches, sometimes the inflorescence condensed in dense verticillasters of flowers, only rarely completely indeterminate [Figs. 695,700,701]; ovules attached to lateral partitions and not the carpel margins; plants commonly with mint-, pennyroyal-, or citrus-scented foliage (in part)
-
16b. Carpels 2, each carpel unlobed, therefore, the gynoecium appearing to be composed of 2 carpels (appearing unicarpellate in Phryma, but the stigmas 2); fruit a capsule or achene
-
19a. Fruit an achene; ovary unilocular and uniovulate; calyx tightly reflexed in fruit [Fig. 764] (in part)
-
19b. Fruit a capsule; ovary bilocular or unilocular in holoparasitic genera, with 2 or more ovules; calyx not reflexed in fruit
-
20a. Fruit a drupe-like capsule 10–20 cm long, with a fleshy exocarp that separates from the woody endocarp, prolonged at the apex into a curved beak that splits into 2 halves at maturity; plants pubescent with stipitate glands, the gland composed of 4 or more mucilage-filled cells
-
20b. Fruit a capsule without a fleshy exocarp, not terminated by a long, 2-pronged beak; plants stipitate-glandular or not, but never slimy-pubescent
-
21a. Anthers with 1 locule, dehiscing by a single, transverse, distal slit, not sagittate at the base (in part)
-
21b. Anthers with 2 locules, dehiscing by 2 longitudinal slits or the locules connate near the apex and opening by a distal, V-shaped slit, usually sagittate at the base
-
22a. Plants holoparasitic, lacking chlorophyll; ovary unilocular, with parietal placentation (in part)
-
22b. Plants autotrophic or hemiparasitic, with chlorophyll; ovary bilocular, with axile placentation
-
23b. Autotrophic herbs, usually not darkening in drying; corolla not galeate (with a galea in Chelone)
-
24a. Androecium with 2 stamens, each stamen with 2 pollen sacs positioned perpendicular to one another—the upper pollen sac positioned transversely to the filament, the lower 1 positioned parallel to the filament; fruit an explosively dehiscent, loculicidal capsule
-
24b. Androecium with 1–4 stamens, the stamens with parallel to somewhat divergent pollen sacs (with respect to each other); fruit a loculicidal or septicidal capsule, but not explosively dehiscent
-
25a. Calyx with a pronounced, tubular, connate portion [Fig. 763]; capsule dehiscence loculicidal; stigma with 2 plate-like lobes that close after contact (in part)
-
25b. Calyx connate at the base, but the connate portion not elongate; capsule dehiscence septicidal; stigmas with 2 lobes that remain open after contact (these plate-like in Gratiola)
-
26a. Lower pair of stamens (which are sterile in our species) with the filament axis bent completely back on themselves and then curved again, therefore, the filaments appearing forked
-
26b. Lower pair of stamens without a conspicuously curved filament axis
-
27a. Amphibious plants of tidal shores with horizontal stems emitting at the nodes clusters of linear leaves and sometimes also peduncles bearing a solitary flower with a ± actinomorphic corolla (in part)
-
27b. Terrestrial or non-tidal wetland plants with prostrate to, more commonly, upright stems and variable leaf shapes, though mostly wider than linear, with inflorescences borne on a stem bearing flowers with weakly to conspicuously zygomorphic corollas (in part)
-
-
-
-
-
-
-
-
-
-
-
-
-
Show photos of:
Each photo represents one family in this group.