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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.

 

CUSCUTA DODDER

Mihai Costea & Saša Stefanović


Vine, annual (perennial herb if on perennial host), not in contact with ground, attached to, holoparasitic on host by many small, specialized roots (haustoria) along stem, generally glabrous. Stem: thread-like, ± green, yellow, orange, or ± red. Leaf: 0 or scale-like, alternate, ± 2 mm. Inflorescence: generally cyme, head- to panicle-like (flowers 1), subtended by 0–3 bracts. Flower: bisexual, radial, parts generally in 4s or 5s; calyx generally divided 2/5–3/5, persistent generally ± cream-white; corolla generally ± white, persistent (withered in fruit) or not, tube cup-shaped to cylindric, bulged or horizontally ridged below lobes or generally not, generally with scales subtending stamens, lobes alternate stamens, erect to reflexed; ovary superior, chambers 2, each 2-ovuled, styles 2, generally free, persistent, stigmas 2, generally spheric, persistent. Fruit: capsule, generally indehiscent to irregularly dehiscent (or circumscissile near base), spheric to ovoid, depressed or not, thickened and/or raised around generally inconspicuous opening between styles or not. Seed: 1–4; coat papillate when hydrated, honeycombed when dry, (rarely neither, with cells ± rectangular, in ± jigsaw-puzzle-like arrangement); embryo generally slender, 1–3-coiled.
± 180 species: cosmopolitan, especially warmer regions of western hemisphere and Polynesia. (Aramaic, Hebrew; to cover, from habit) [Costea & Stefanovic 2009 Syst Bot 34:570–579] By persistent, withered corolla, fruit may be "capped" (corolla on top of fruit), "surrounded" (fruit at least in part visible, corolla ± loosely around fruit), or "enclosed" (fruit not visible, corolla ± tightly around fruit). Cuscuta pentagona Engelm. excluded.
Unabridged etymology: (Aramaic, Hebrew; from the verb K-S-Y (Kaph, Shin, Yodh), to cover, from habit)
Unabridged references: [Costea et al. 2005 Brittonia 57:264–272; Costea et al. 2006 Sida 22:151–175, 177–195, 197–207, 209–225; Costea & Stefanovic 2009. Cuscuta jepsonii (Convolvulaceae), an invasive weed or an extinct endemic? Amer J Bot 96:1744–1750; Costea et al. 2009. Untangling the systematics of salt marsh dodders: Cuscuta pacifica a new segregate species from Cuscuta salina (Convolvulaceae). Syst Bot 34:787–795; Costea & Stefanovic. 2009. Molecular phylogeny of Cuscuta californica complex (Convolvulaceae) and a new species from New Mexico and Trans-Pecos. Syst Bot 34:570–579; Costea & Tardif 2006 Canad J Plant Sci 86:293–316]

Key to Cuscuta

1. Styles 2, fused (Subg. Monogynella)

2. Style >= stigmas ..... [C. japonica var. formosana]

2' Style < stigmas. (Extirpated) ..... [C. reflexa]

1' Styles 2, free

3. Stigmas elongate; calyx abruptly narrowed to short, obtuse, fleshy appendage (Subg. Cuscuta) ..... C. approximata

3' Stigmas spheric to widely elliptic; calyx lobes not narrowed to appendage (Subg. Grammica)

4. Corolla scales 0

5. Corolla lobes 1/3–1/2 tube, ovate-triangular, tips incurved ..... C. jepsonii

5' Corolla lobes 3/4 to > tube, narrowly lanceolate to lanceolate, tips not incurved

6. Styles 0.5–1(1.5) mm; anthers 0.25–0.5 mm, wide-elliptic; fruit translucent, surrounded by corolla ..... C. occidentalis

6' Styles 1.2–3 mm; anthers 0.7–1.1 mm, oblong to linear; fruit not translucent, ± enclosed by corolla (top not or barely visible)

7. Calyx 1/2–1/4 corolla tube; corolla lobes <= tube; filaments 0.2–0.6 mm ..... C. brachycalyx

7' Calyx 3/4 to = corolla tube; corolla lobes >= tube; filaments 0.6–1.1 mm ..... C. californica

8. Ovary, fruit ovoid-conic, tip pointed; seed 1 ..... var. apiculata

8' Ovary, fruit spheric to spheric-depressed; seeds (1)2–4

9. Perianth, pedicels dense-papillate ..... var. papillosa

9' Perianth, pedicels not papillate ..... var. californica

4' Corolla scales present

10. Corolla scales generally reduced, shallowly finely dentate (rarely 2-lobed, ± fringed into 1–3 short units on each side of filaments) ..... C. suksdorfii

10' Corolla scales well developed, fringed

11. Calyx, corolla lobe tips dissimilar, calyx lobe tips obtuse to rounded, corolla lobe tips acute

12. Calyx 1/2–3/4 corolla tube. (Extirpated) ..... C. suaveolens

12' Calyx generally ± = corolla tube ..... C. campestris

11' Calyx, corolla lobes tips similar, both either acute to long-acuminate or obtuse to rounded

13. Calyx, corolla lobes obtuse to rounded

14. Calyx veined, shiny; calyx, corolla lobes finely dentate; seeds 1, spheric to spheric-ovoid ..... C. denticulata

14' Calyx not veined, not shiny; calyx, corolla lobes entire or calyx lobes finely serrate; seeds (1)2–4

15. Flower parts in (3s)4s(5s); fruit capped by corolla ..... C. cephalanthi

15' Flower parts in (4s)5s; fruit surrounded by corolla. (Extirpated) ..... C. obtusiflora var. glandulosa

13' Calyx, corolla lobes acute to long-acuminate

16. Corolla lobe tips incurved ..... C. indecora var. indecora

16' Corolla lobe tips straight or recurved but not incurved

17. Embryo enlarged on 1 end

18. Flowers 1–2(5), (2.8)3–4(5) mm; calyx lobes lanceolate, ± entire; anthers 0.4–0.7 mm, filaments (0)0.1–0.3 mm; desert, on shrubs in Atriplex, Ambrosia, Psorothamnus, Xylorhiza ..... C. nevadensis

18' Flowers (1)2–5, 1.9–3.2 mm; calyx lobes oblong to obovate-rhombic, ± irregularly finely dentate; anthers 0.3–0.4 mm, filaments 0.2–0.4 mm; desert, on Bursera, Schinus. (Extirpated) ..... C. veatchii

17' Embryo not enlarged on 1 end

19. Flower 5–7(9) mm; calyx generally 1/2 corolla tube, lobe bases overlapped; corolla lobes 1/4–1/3 tube; anthers 0.8–2 mm ..... C. subinclusa

19' Flower 2.5–5(6) mm; calyx generally ± = corolla tube, lobe bases generally not overlapped; corolla lobes generally ± = tube; anthers 0.3–0.7 mm

20. Flowers in host inflorescence, parts in 4s(5s); calyx, corolla lobes acuminate to long-acuminate; fruit spheric to spheric-depressed, not thickened, not raised around opening between styles; seeds 1–4 ..... C. howelliana

20' Flowers not in host inflorescence, parts in 5s; calyx, corolla lobes acute to acuminate; fruit elliptic-ovoid, ± thickened, ± raised around opening between styles; seeds 1–2

21. Pedicels (0.5)1–5 mm; flower 2.5–4.5 mm; corolla tube ± cylindric, lobes reflexed to spreading, ovate- to lance-oblong; inland salt flats ..... C. salina

21' Pedicels 0.5–2 mm; flower 3.5–6 mm; corolla tube bell-shaped, lobes spreading to erect, widely ovate; coastal salt marshes, interdune depressions, tidal flats ..... C. pacifica

22. Pedicels, calyx papillate; interdune depressions ..... var. papillata

22' Pedicels, calyx not papillate; coastal salt marshes, tidal flats ..... var. pacifica

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