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Geranium

See list of 14 species in this genus

The gynoecium of Geranium is composed of 5 connate carpels that form a compound ovary. Each carpel is made up of a basal, thickened portion called the mericarp body (which contains the ovules) and an elongate, apical portion called the carpel beak (which is adnate to and conceals the style column prior to fruit maturation). The carpel beaks separate from the style column and outwardly curve at maturity, remaining attached to the style column near or at its apex. In most species of Geranium, the carpel beaks do not split all the way to the style remains. The region between the apex of the dehisced carpel beaks and the style remains is called the style beak and can be seen as a narrowed portion near the apex of the intact carpel beaks prior to separation. Above the carpel beaks project the styles. References: Aedo (2000, 2001).

  • 1a. Leaves palmately compound, the terminal segment petiolulate; mericarp bodies separating from the carpel beaks but remaining attached to the style column for a period of time by 2 subapical filaments
  • 1b. Leaves palmately lobed, the leaf segments confluent; mericarp bodies remaining attached to the carpel beaks, without subapical filaments
    • 2a. Petals 12–20 mm long [Fig. 673]; anthers 2–2.6 mm long; style beaks 4–8 mm long; plants perennial from a stout rhizome
      • 3a. Each cymule of the inflorescence usually 1-flowered; stems with several leaves; petals retuse at the apex, deep red (rarely white)
      • 3b. Each cymule of the inflorescence usually 2-flowered; stems with a single pair of leaves, the other leaves basal; petals entire or very slightly retuse at the apex, blue-purple or pink (rarely white)
        • 4a. Sepals, pedicels, and style beaks with stipitate glands [Fig. 673]; pedicels deflexed after anthesis; petals blue to blue-purple, 12–13 mm wide, 1.5–2.1 times as long as wide [Fig. 673]
        • 4b. Sepals, pedicels, and style beaks pubescent but not glandular; pedicels suberect after anthesis; petals pink to pink-purple (rarely white), 8.5–11.6 mm wide, 1.3–1.4 times as long as wide
    • 2b. Petals 2.5–10 mm long; anthers 0.4–1.5 mm long; style beaks 0–6 mm long; plants annual or biennial, commonly from a taproot, or perennial with rhizomes in G. pyrenaicum, G. sibiricum, and G. thunbergii
      • 5a. From 3–5 of the 5 outer stamens sterile and lacking anthers; seeds smooth; petals 2.5–4 mm long
      • 5b. All of the stamens fertile and bearing anthers; seeds reticulate or striate, sometimes obscurely so (+/- smooth in G. aequale and G. pyrenaicum); petals (3–) 3.2–10 mm long
        • 6a. Sepals obtuse to acute at the apex, sometimes with a short mucro 0.1–0.3 mm long; mericarp bodies glabrous on most of the surfaces (pubescent in G. pyrenaicum, ciliate near the base in G. aequale), cross-wrinkled or smooth; seeds ± smooth or striate
          • 7a. Mericarp bodies pubescent; plant perennial from a short, vertical rhizome; seeds 2.2–2.7 mm long; petals 7–11 mm long
          • 7b. Mericarp bodies glabrous (though ciliate near the base in G. aequale); plants annual; seeds 1.4–1.8 mm long; petals (3–) 3.5–8.5 (–10) mm long
            • 8a. Mericarp bodies cross-wrinkled, eciliate; seeds striate; anthers 0.7–1.5 mm long; petals (3–) 4.5–8.5 (–10.5) mm long; pedicels 2.3–4.2 times as long as the sepals
            • 8b. Mericarp bodies smooth, densely ciliate near the base; seeds ± smooth; anthers 0.4–0.6 mm long; petals 3.5–4.5 mm long; pedicels 1.5–2.5 times as long as the sepals
        • 6b. Sepals acuminate at the apex, tipped with an awn 0.5–2 mm long [Figs. 671,672]; mericarp bodies at least sparsely hirsute (sometimes nearly glabrous in 
 G. columbinum), smooth; seeds reticulate
          • 9a. Pedicels 3–13 mm long, 0.6–2.2 times as long as the sepals; style beak 1–2 mm long
            • 10a. Mericarp bodies pubescent with antrorsely oriented, eglandular hairs 
ca. 1 mm long; seeds inconspicuously reticulate-patterned with irregular, thin-walled aereolae; ultimate segments of middle and upper stem leaves usually narrow-oblong and obtuse at the apex
            • 10b. Mericarp bodies pubescent with spreading, often glandular, hairs 
0.2–0.6 mm long; seeds conspicuously reticulate-patterened with ± uniform, thick-walled aereolae; ultimate segments of middle and upper stem leaves usually linear and acute at the apex
          • 9b. Pedicels 10–60 mm long, 1.8–8.2 times as long as the sepals [Fig. 671]; style beak 0–0.5 (–1) mm long or 3.5–4.5 mm long

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