Floret Pedicel Ray Bract Peduncle Inflorescence parts Inflorescence Types © KPU.ca/Hort Cyme: the growing tip becomes a floret before more arise from axillary buds. May appear corymb-like. Sometimes head inflorescences are arranged in cymes. Inflorescence Types © KPU.ca/Hort Raceme: elongated inflorescence with floret pedicels of about equal length that develop along a rachis. Inflorescence Types © KPU.ca/Hort Spike: inflorescence elongate and raceme-like but with very short or no pedicels. Occasionally head-like due to very short internodes, but these are not in the Asteraceae. Inflorescence Types © KPU.ca/Hort Verticillaster: florets occurring in false whorls at nodes on a elongate stalk usually with pedicels and leaf-like bracts. May appear head-like (due to very short internodes), or spike- like. Members of the Lamiaceae only (mint family). Inflorescence Types © KPU.ca/Hort Umbel: pedicels (and rays if a compound umbel) of about equal length all arising from the apex of the peduncle. A family feature of the Apiaceae but also occurs in other families. Inflorescence Types © KPU.ca/Hort Corymb: florets are formed on lateral stalks of different length, the longest being at the base creating a flat-topped inflorescence. Inflorescence Types © KPU.ca/Hort Panicle: a main axis supports several racemes so that the inflorescence appears branched. Term often applied to any highly branched, elongate, inflorescence whose flowering sequence is unclear, even if the branching is cymose (which botanically is a thyrse) Inflorescence Types © KPU.ca/Hort Catkin: florets unisexual, lack petals, and tightly packed together on a rachis that usually droops downward (found only in some woody dicots, e.g. willow, birch, alder, oak). Inflorescence Types © KPU.ca/Hort Spadix: racemose inflorescence consisting of many tiny florets on an enlarged fleshy axis which is usually partially enclosed by a large bract (the spathe). In the Araceae only. Inflorescence Types © KPU.ca/Hort Spikelet: inflorescence consisting of an axis (rachilla), above two bracts (glumes) and one or more very small florets with perianths reduced to paired bracts (the palea and lemma). Spikelets may be arranged in spikes, racemes, or panicles. Found in grasses and sedges. Inflorescence Types © KPU.ca/Hort Head (Asteraceae): florets small, closely packed, lack pedicels, and arise from a flattened axis that is surrounded or subtended by bracts to appear as a large flower. Head inflorescences may be arranged in cymes, and may be small with only a few disk florets. Inflorescence Types © KPU.ca/Hort Heads can be very small! Head: florets small, closely packed, lack pedicels, and arise from a flattened axis that is surrounded or subtended by bracts to appear as a large flower. Asteraceae. Inflorescence Types © KPU.ca/Hort Cyathium: consists of a simple female floret (one pistil) in the center surrounded by many simple male florets (one stamen each) on bracts. Found only in the Euphorbiaceae. FYI Inflorescence Types © KPU.ca/Hort Use the Key to the Basic Inflorescence Types in your lab manual or lecture handouts to identify the following unknowns. Practice identifying inflorescence unknowns Inflorescence Types © KPU.ca/Hort Unknown #1 Inflorescence Types © KPU.ca/Hort Unknown #2 Inflorescence Types © KPU.ca/Hort Unknown #3 Inflorescence Types © KPU.ca/Hort Unknown #4 Inflorescence Types © KPU.ca/Hort Unknown #5 Inflorescence Types © KPU.ca/Hort Unknown #6 Inflorescence Types © KPU.ca/Hort Unknown #7 Inflorescence Types © KPU.ca/Hort Unknown #8 Inflorescence Types © KPU.ca/Hort Unknown #9 Inflorescence Types © KPU.ca/Hort Unknown #10 Inflorescence Types © KPU.ca/Hort Unknown #11 Inflorescence Types © KPU.ca/Hort Answer Key 1) Catkin 2) Verticillaster 3) Head 4) Corymb 5) Raceme 6) Panicle 7) Spikelet (arranged in a panicle) 8) Cyme 9) Spadix Use the KPU Plant Database to search for more inflorescence type examples: 10) Spike Morphological Search, click Expand 11) Umbel > Inflorescence Type Inflorescence Types © KPU.ca/Hort .