From the Introduction to the Glossary at APweb

1. From the Introduction to the Glossary at APweb The most important thing to remember when using this (or any other) glossary is that just because some aspect of an organism is dignified by a sesquipedalian term, this by no mean signifies that it is "real". Definitions should as far as possible follow current usage, rather than etymology or original definitions. However, current usage may not be consistent, and this is one of the major failings of botanical terminology. As Rickett (1954 p. 2; emphasis in original) noted, "To be uncertain whether "glabrous" means "free from hairs and roughness" or only "free from hairs" is as bad as if pi should stand sometimes for the ratio of a circle to its diameter and sometimes for something else; or as if Cu meant sometimes "copper" and sometimes "brass". Yet this is the state of affairs in botany today". Over forty years later, this is still true, but we should be attempting to reach consensus here, too.

2. Inflorescence Subflorescence Florescence Flower Inflorescence Types Includes Inflorescence, Florescence, and Flower Shoots Multiple criteria used to define a particular type Defined by Minimal Inflorescence Unit (MIU), usually the Florescence Defined by how MIUs are borne on the Reproductive Shoot, the Inflorescence Defined as determinate or indeterminate in two senses Defined by developmental mechanism and by final result Here, all nodes have lateral determinate organs so they can more easily be recognized as nodes

3. Inflorescence Types Two somewhat independent criteria of Determinacy of Inflorescence The first sense: Behavior of the Florescence SAM Defined as determinate if Florescence SAM converts to Flower SAM Defined as indeterminate if it continues to makes florescence phytomeres Figures should indicate if there is a terminal flower or no terminal flower The second sense: Order of Flower Opening Defined as determinate if top/distal/central flowers open first; defined as indeterminate if bottom/proximal/peripheral flowers open first Figures should indicate the order of opening by the size of the flower. Smaller flowers are understood to open later than, after than, larger flowers. In – In Det – In In – Det Det - Det Probably Illegal

4. Blue, Indeterminate or Determinate in the First Sense Red, Indeterminate or Determinate in the Second Sense In-In In-In Det-In Det-In Det-In Det-Det Det-Det Det-In In-In Simple Compound Dichasium Dichasium This is a compound raceme Det-ps In Det-Det Det-Det Det-Det Figure 10-13 Walters and Keil This is a panicle

5. Simple Raceme = a Florescence PedicelledFlowers Simple Spike = a Florescence Sessile Flowers Pedicel ‘Simple Compoundness’: 2o a complete copy of the 1o Bract Rachis Peduncle Cauline Leaf Compound Spike contains a Subflorescence Spikes arranged as a Raceme Compound Raceme contains a Subflorescence Racemes arranged as a Raceme Indeterminate (in the first sense) Types of Reproductive Shoots Primary and Secondary Florescence SAMs ( ) remain indeterminate Probably always indeterminate in the second sense

6. Simple Corymb Raceme with differentially-elongate pedicels, resulting in round- or flat-topped florescence Compound Corymb Contains a Subflorescence Corymbs arranged in a Corymb Pedicel Rachis Bract Cauline Leaf Peduncle ‘Simple Compoundness’: 2o a complete copy of the 1o Indeterminate (in the first sense) Types of Reproductive Shoots Primary and Secondary Florescence SAMs ( ) remain indeterminate Probably always indeterminate in the second sense

7. Bract A foreshortened Raceme A foreshortened Spike Determinate (in the first sense) Inflorescence Types Superficially no Primary Shoot because of very short internodes Fascicles with pedicelled flowers; pedicels are flexis Glomerules with sessile flowers Probably always indeterminate in the second sense

8. Simple UmbelsCompound Umbel A foreshortened Corymb Umbels arranged in an Umbel (2o peduncles) The second sense of determinacy: top/distal/central flower opens first in the second sense This is not branchable, unlike compound spikes, racemes, and coryms Determinate (in the first sense) Inflorescence Types Superficially no Primary Shoot because of very short internodes Umbel with pedicelled flowers inserted into a small head-like receptacle Pedicels (and rays) are stiff

9. LODs within and subtending Inflorescences 1) if subtending and one per flower, it is a floral (or subfloral) bract 2) if one and subtending a florescence, then an inflorescence bract; origin a cauline leaf subtending an axis of bractless flowers 3) if several and subtending a florescence, then collectively aninvolucre; origin a foreshortened axis of flowers with retained bracts (Umbel)or origin a foreshortened subflorescence-containing

10. Cyanthium Spikelet Compressed spike Poaceae Head/Capitulum Asteraceae Spadix Spike with fleshy rachis Hypanthodium Other Inflorescence Types

11. At this point a Determinate (Flower) SAM Axillary (Flower) SAM At this point an Indeterminate (Florescence) SAM 1 2 3 Dichasium or if sessile then a Cyme Determinate Inflorescence Types The Simple Cymes (Often) Opposite Phylotaxy in a Florescence Shoot; Determinate in both senses 1. Nonbranching Fundamental Unit, a Dichasium or a Cyme; ‘Unit of Three’ 2. Central Flower SAM aborts; ‘Dichotomously Branching’ 3. One Axillary Flower SAM aborts; Zig-zag, secund, depending on phylotaxy The opposite two bracts mark the last Florescence Node and axillary SAMs

12. Present Indeterminate (Florescence) SAM 1 2 3 Dichasium or if sessile then a Cyme • Determinate Inflorescence Types • The Non-Simple Cymes • (Usually) Opposite Phylotaxy in a Florescence Shoot and • Determinate in the second sense • Nonbranching Fundamental Unit, a Dichasium • 2. One Axillary SAM is a functioning Florescence SAM • 3. Both Axillary SAMs are functioning Florescence SAMs • The opposite two bracts mark the last Florescence Node and axillary SAMs

13. Peduncle Pedunclulate Dichasiums arranged Dichasiums arranged as a Dichasium as a Cyme (Peduncled secondaries) (Sessile secondaries) Determinate Inflorescence Types The simple and compound Cymes Higher-order compound inflorescences are usually dichotomously branched, hence the term ‘dichasium’ for the responsible minimum unit

14. 0 2 2 1 1 2 2 2 2 Simple Twice Compound Compound Dichasiums/Cymes have a Different Kind of Compoundness This kind is the same as seen in compound leaves

15. decussite Helicoid Cyme Compound Dichasium Compound Monochasium distichous Drepanium Determinate Inflorescence Types Compound Cymes made from differential outgrowth Higher-order compound inflorescences from development of axis on the same side of the primary axis

16. decussite Scorpiod Cyme Compound Dichasium Compound Monochasium distichous Rhipidium Determinate Inflorescence Types Compound Cymes made from differential outgrowth Higher-order compound inflorescences from development of axis on alternating sides of the primary axis

17. 0 0 0 2 1 1 This looks like a panicle of a grass Determinate Inflorescence Types Creation of a Twice-Compound Rhipidium from an Alternating Phylotaxy Higher-order compound inflorescences from development of axis on alternating sides of the primary axis

18. A simpler view of Cymes (Mostly All Wrong) Determinant (?) Inflorescences: Cyme: composed of usually numerous 3-flowered units Cymes can be of many different shapes due to differences in branching pattern Cyme: ‘cabbage sprout’ These are secondary inflorescences Dichasium Compound Dichasium Rhipidiums A determinate Umbel

19. Panicle Rhipidiums arranged as a Raceme (often confused with a Compound Raceme) Rhipidiums arranged as a Corymb (often confused with a Compound Corymb) Secondary Inflorescence Types MIU is of a Type different than that of the shoot Lower flowers usually develop first, but sequence may be reversed

20. Heads arranged as a determinate Compound Corymb or Panicle Verticillaster Verticils arranged as a Spike Thyrse Compound Dichasiums arranged as a Raceme Catkin/Ament Compound Dichasiums arranged as a Spike Unbranchable; differentiates this from the earlier Compound Spike Spikelets arranged as a Panicle (Rhipidiums arranged as a Raceme) Spikes arranged as a Raceme Secondary Inflorescence Types MIU is of a Type different than that of the shoot Lower flowers usually develop first, but sequence may be reversed

21. An alternative definition of a Panicle: know it but don’t use it Raceme: Flowers, with pedicels, arranged on a long axis = rachis. Defined by most as indeterminate in both senses. Unbranched, so it is a florescence. Compound Raceme, called by some a Panicle: Different than the first Compound Raceme, the 2o are not branchable. Walters and Keil

22. Dichasium Dichasium Dichasium Compound Dichasium (showing only one lateral) Potentilla recta Linnaeus MIU is a dichasium, arranged in compound dichasia, which are arranged in a determinate spike/raceme Spike

23. Compound and Multiple-compound Rhipidium