Inflorescences

I. Definition: a group of two or more flowers on a floral axis

II. Criteria for interpretation

A. Position

1. Axillary (Angelonia)
2. Terminal (Pittospermum)
3. Basal. Plant with a scape [= scapose] (Viola, Pyrola)

B. Number of flowers

1. Solitary (Magnolia)
2. More than one

C. Extra-floral features

1. Bracts (Bougainvillea, Poinsettia)
2. Pedicels (Cuphea)
3. Peduncle (Amyema)

III. Sequence of flowering

A. Determinate

1. Dichasium (cyme)

a. simple (Hypericum)
b. compound (Kalanchoe)

2. Monochasium

a. simple (Dianthus)
b. compound (Sedum) including scorpioid/helicoid cymes (Lithospermum)

B. Indeterminate

1. Raceme (Rivina, Roripa)
2. Panicle (Cornus)
3. Spike (Agastache)
4. Corymb
5. Umbel (Hoya, Asclepias)
6. Head or capitulum (various Asteraceae such as Pseudogynoxys, Eryngium)
7. Catkin or ament (Betula)
8. Spadix (Arisaema, various Araceae)
9. Verticel (Lycopus, Monarda)

IV. Inflorescence Combinations

A. Panicle of spikelets (Calamagrostis)
B. Umbel of umbels (Daucus)
C. Spike of heads (Liatris)
D. Corymb of heads (Achillea)
E. Spike of spikelets (Cyperus, Hordeum and various other grasses)

V. Special Types of Inflorescences

A. Cyathium (Euphorbia, Euphorbiaceae)
B. Syconium (Ficus, Moraceae)


SIUC / College of Science / Elements of Plant Systematics
URL: http://www.plantbiology.siu.edu/PLB304/Inflorescences.html
Last updated: 17-Feb-08 / dln