A foundation monograph of Ipomoea (Convolvulaceae) in the New World

Dichotomous keys

Keys are provided in a somewhat unconventional way and it is recommended that users follow the suggested steps in the order provided. Species in Steps 1–3 below also appear in the appropriate geographical keys. Note that species may enter several times in different places in the keys.
Step I. Does the plant fit any of the following distinct groups?
1. Plants of seashore (rarely inland in saline habitats): Ipomoea pes-caprae (pink flowers, retuse leaves), I. violacea (white to pale violet flowers, exserted stamens), I. imperati (white flowers, creeping herb), I. littoralis (Hawaii), I. sagittata (Caribbean and North American–sagittate lvs), I. macrorhiza (United States–white flowers, pubescent sepals).
2. Plants with a hirsute ovary and capsule: Ipomoea sidifolia, I. dasycarpa, I. velutinifolia, species in the Batatas Clade (page 387).
Step II. Is the plant one of the following very distinctive widespread common species?
An erect plant with ovate cordate leaves and pink flowers: 84b. I. carnea subsp. fistulosa.
A slender plant with pinnate leaves, pseudo-stipules and dark red corollas: 312. I. quamoclit.
A twining vine with pure white flowers, a narrowly cylindrical corolla tube and strongly awned sepals: 272. I. alba.
Step III. Does the plant belong to one of the following distinctive clades?
The Arborescens Clade (page 263). Trees, shrubs or lianas with white latex. Leaves entire. Sepals ovate or oblong, somewhat coriaceous. Corolla white, often with dark centre, glabrous or pubescent anthers included; seeds with long white marginal hairs.
The Batatas Clade (page 387) Annual or perennial herbs. Leaves entire or lobed. Sepals thin, often papery, usually distinctly mucronate. Corolla always glabrous, white or pink, often with a dark throat, often small and campanulate. Ovary and capsule often hirsute.
The Pharbitis Clade (page 430) Annual or perennial herbs, often hirsute. Leaves lobed or entire. Bracteoles often persistent. Sepals usually relatively large, usually with elongate, somewhat accrescent apex, sometimes leafy in texture. Corolla usually showy, pink, blue or violet, glabrous or (less commonly) pubescent. Stigma usually 3-lobed and ovary 3-locular. Capsule up to 6-seeded.
The Quamoclit Clade (page 556) Slender, twining usually annual, herbaceous herbs. Sepals characteristically awned, the awn subterminal on the abaxial surface, often equalling the sepal proper. Corolla red, orange or yellow, suburceolate or hypocrateriform, glabrous, stamens exserted or at least held at mouth of corolla. Ovary and capsule 4-locular.
Step IV. If your plant cannot be placed using Steps 1–3, go to the appropriate geographical key:
A. South American continent including the Galapagos Islands (page 54)
B. The North American Continent from Panama northwards (page 78)
C. The Caribbean Islands including Bermuda, Trinidad and the Netherlands Antilles (page 93)
D. Hawaii (page 99)
The two continental keys are divided into a series of subkeys to facilitate access as they would otherwise be very large. Some species can be accessed through different routes so individual species may occur in several subkeys.