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.

From the Introduction to the Glossary at APweb

Inflorescence TypesIncludes Inflorescence, Florescence, and Flower Shoots

Multiple criteria used to define a particular type

Defined by Minimal Inflorescence Unit (MIU), usually the FlorescenceDefined by how MIUs are borne on the Reproductive Shoot, the Inflorescence

Defined as determinate or indeterminate in two sensesDefined by developmental mechanism and by final result

Here, all nodes have lateral determinate organs so they can more easily be recognized as nodes

InflorescenceSubflorescence Florescence

Flower

Inflorescence TypesTwo 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.

Probably IllegalIn – In Det – In In – Det Det - Det

Figure 10-13 Walters and Keil

In-In In-In Det-In Det-In Det-In

Det-In In-In Det-Det Det-Det

Det-ps In Det-Det Det-Det Det-Det

Blue, Indeterminate or Determinate in the First SenseRed, Indeterminate or Determinate in the Second Sense

This is a compound raceme

This is a panicle

Simple CompoundDichasium Dichasium

Simple Raceme = a FlorescencePedicelled Flowers

Compound Spike contains a SubflorescenceSpikes arranged as a Raceme

Indeterminate (in the first sense) Types of Reproductive ShootsPrimary and Secondary Florescence SAMs ( ) remain indeterminate

Probably always indeterminate in the second sense

Simple Spike = a FlorescenceSessile Flowers

Compound Raceme contains a SubflorescenceRacemes arranged as a Raceme

‘Simple Compoundness’: 2o a complete copy of the 1o

Peduncle

RachisPedicelBract

Cauline Leaf

Probably always indeterminate in the second sense

Simple CorymbRaceme with differentially-elongate pedicels, resulting in round- or flat-topped florescence

Compound CorymbContains a Subflorescence

Corymbs arranged in a Corymb

Indeterminate (in the first sense) Types of Reproductive ShootsPrimary and Secondary Florescence SAMs ( ) remain indeterminate

‘Simple Compoundness’: 2o a complete copy of the 1o

Peduncle

Rachis

Pedicel

BractCauline Leaf

Determinate (in the first sense) Inflorescence TypesSuperficially 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

Bract

A foreshortened Raceme A foreshortened Spike

Determinate (in the first sense) Inflorescence TypesSuperficially no Primary Shoot because of very short internodes

Umbel with pedicelled flowers inserted into a small head-like receptaclePedicels (and rays) are stiff

The second sense of determinacy:top/distal/central flower opens first

Simple Umbels Compound Umbel A foreshortened Corymb Umbels arranged in an Umbel

in the second sense This is not branchable, unlike

compound spikes, racemes, and coryms

(2o peduncles)

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 an involucre; origin a foreshortened axis of flowers with retained bracts (Umbel) or origin a foreshortened subflorescence-containing

Other Inflorescence Types

SpadixSpike with

fleshy rachis

Hypanthodium

Cyanthium

SpikeletCompressed spike

Poaceae

Head/CapitulumAsteraceae

Determinate Inflorescence TypesThe Simple Cymes

(Often) Opposite Phylotaxy in a Florescence Shoot; Determinate in both senses1. 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 phylotaxyThe opposite two bracts mark the last Florescence Node and axillary SAMs

1 2 3

At this point an Indeterminate (Florescence) SAM

At this point a Determinate (Flower) SAM

Dichasium or if sessile then a Cyme

Axillary (Flower) SAM

Determinate Inflorescence TypesThe Non-Simple Cymes

(Usually) Opposite Phylotaxy in a Florescence Shoot andDeterminate in the second sense

1. Nonbranching Fundamental Unit, a Dichasium2. One Axillary SAM is a functioning Florescence SAM

3. Both Axillary SAMs are functioning Florescence SAMsThe opposite two bracts mark the last Florescence Node and axillary SAMs

1 2 3

Present Indeterminate (Florescence) SAM

Dichasium or if sessile then a Cyme

Determinate Inflorescence TypesThe simple and compound Cymes

Higher-order compound inflorescences are usually dichotomously branched, hence the term ‘dichasium’ for the responsible minimum unit

Pedunclulate Dichasiums arranged Dichasiums arranged as a Dichasium as a Cyme (Peduncled secondaries) (Sessile secondaries)

Peduncle

Simple Twice Compound

Compound Dichasiums/Cymes have a Different Kind of CompoundnessThis kind is the same as seen in compound leaves

0

1 12 2

2 22 2

Determinate Inflorescence TypesCompound Cymes made from differential outgrowth

Higher-order compound inflorescences from development of axis on the same side of the primary axis

decussite

distichous

Compound Dichasium

Helicoid Cyme

Drepanium

CompoundMonochasium

Determinate Inflorescence TypesCompound Cymes made from differential outgrowth

Higher-order compound inflorescences from development of axis on alternating sides of the primary axis

distichous

Scorpiod Cyme Compound Dichasium

decussite

Rhipidium

CompoundMonochasium

Determinate Inflorescence TypesCreation of a Twice-Compound Rhipidium from an Alternating Phylotaxy

Higher-order compound inflorescences from development of axis on alternating sides of the primary axis

0 0 0

1 1

2

This looks likea panicle of a

grass

Determinant (?) Inflorescences:Cyme: composed of usually numerous 3-flowered unitsCymes can be of many different shapes due to differences in branching patternCyme: ‘cabbage sprout’

A simpler view of Cymes (Mostly All Wrong)

These are secondary inflorescences

A determinate Umbel

Dichasium Compound Dichasium

Rhipidiums

Secondary Inflorescence TypesMIU is of a Type different than that of the shoot

Rhipidiums arranged as a Corymb

(often confused with aCompound Corymb)

PanicleRhipidiums arranged

as a Raceme(often confused with aCompound Raceme)

Lower flowers usually develop first, but sequence may be reversed

Spikes arrangedas a Raceme

Unbranchable; differentiates this from the earlier Compound Spike

Secondary Inflorescence TypesMIU is of a Type different than that of the shoot

Verticillaster

Verticils arranged as a Spike

Catkin/AmentCompound Dichasiums

arranged as a Spike

Heads arranged as adeterminate Compound

Corymb or Panicle

Spikelets arrangedas a Panicle (Rhipidiums arranged as a Raceme)

ThyrseCompound Dichasiums arranged as a Raceme

Lower flowers usually develop first, but sequence may be reversed

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 notbranchable.

An alternative definition of a Panicle: know it but don’t use it

Walters and Keil

DichasiumDichasium

Dichasium

Potentilla recta Linnaeus

MIU is a dichasium, arranged in compound dichasia, which arearranged in a determinate spike/raceme

Compound Dichasium(showing only one lateral)

Spike

Compound and Multiple-compoundRhipidium