Aeonium

Webb & Berthelot

Hist. Nat. Îles Canaries 3(2,1): 184, plates 28–35. 1840 ,.

Etymology: Dioscoridean name for A. arboreum
Treatment appears in FNA Volume 8. Treatment on page 167. Mentioned on page 149, 168.

Shrubs [perennial herbs], not viviparous, [1–] 7–10 [–20] dm, glabrous or pubescent. Stems erect, branched [simple], woody or fleshy. Leaves persistent, crowded in rosettes at ends of branches, alternate, sessile, not connate basally; blade oblong-lanceolate or obovate, laminar to terete, 3–15 cm, fleshy, base not spurred, margins ciliate; veins not conspicuous. Inflorescences terminal cymes. Pedicels present. Flowers erect or spreading, [6–] 7–12 [–16] -merous; sepals connate basally, all alike; petals spreading or erect, distinct or nearly so, cream or bright-yellow; calyx and corolla not circumscissile in fruit; nectaries mostly rectangular; stamens 2 times as many as sepals; filaments adnate on corolla base; pistils erect, distinct or nearly so; ovary base rounded; styles 2+ times shorter than ovary. Fruits erect. Seeds ellipsoidal, ribbed, finely cross-ribbed. x = 18.

Distribution

Introduced; Calif., Asia (Yemen), Africa, Atlantic Islands (especially Canary Islands)

Discussion

Species 31 (2 in the flora).

Aeonium and the other polymerous-flowered Macaronesian Crassulaceae were formerly included in the polymerous-flowered Sempervivum. From studies in DNA and molecular systematics, T. H. M. Mes (1995) concluded that Aeonium and these related genera probably evolved from North African Sedum-like ancestors and are only more distantly related to Sempervivum. He thought that the wide range of growth-forms in Aeonium, including the woody habit, is derived from herbaceous ancestors.

Selected References

None.

Key

1 Rosette leaves 50-75, blade bright green, 5-9(-15) cm, 1.5-3 mm thick; petals 9-11, spreading, bright yellow. Aeonium arboreum
1 Rosette leaves 15-25, blade gray-green, 3-6 cm, 2-5 mm thick; petals 7-9, erect, cream. Aeonium haworthii
... more about "Aeonium"
perigynous +  and hypogynous +
Reid V. Moran +
Webb & Berthelot +
lobed +  and toothed +
terete +, obovate +  and oblong-lanceolate +
3 cm30 mm <br />0.03 m <br /> (15 cm150 mm <br />0.15 m <br />) +
not circumscissile +
whorled +, opposite +  and alternate +
not circumscissile +
Calif. +, Asia (Yemen) +, Africa +  and Atlantic Islands (especially Canary Islands) +
Dioscoridean name for A. arboreum +
[6-]7-12[-16]-merous +
spreading;erect +
axillary +  and terminal +
alternate +  and crowded +
persistent +
connate +
semi-inferior +  and superior +
tenuinucellate +, crassinucellate +  and bitegmic +
perigynous +  and hypogynous +
nearly +  and distinct +
erect +  and spreading +
(3-)4-5(-12)[-30+]-carpellate +
nearly +  and distinct +
Hist. Nat. Îles Canaries +
cross-ribbed +  and ribbed +
ellipsoidal +
1 +  and many +
adnate +  and free +
antipetalous +
2 times as many as sepals +
fleshy +  and woody +
distinct +
2+ times shorter than ovary +
Aeonium +
Crassulaceae +
not conspicuous +
perennial +, biennial +  and annual +
pubescent +  and glabrous +