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 Walters and Keil
This is a panicle

5. Indeterminate (in the first sense) Types of Reproductive Shoots
Simple Spike = a Florescence
Sessile Flowers
Simple Raceme = a Florescence
Pedicelled Flowers
‘Simple Compoundness’:
2o a complete copy of the 1o
Bract
Pedicel
Rachis
Cauline Leaf
Peduncle
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. Indeterminate (in the first sense) Types of Reproductive Shoots
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. Determinate (in the first sense) Inflorescence Types
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. Determinate (in the first sense) Inflorescence Types
Simple Umbels Compound 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 an involucre;
origin a foreshortened axis of flowers with retained bracts (Umbel) or
origin a foreshortened subflorescence-containing

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

11. Determinate Inflorescence Types
Axillary
(Flower) SAM
At this point a
Determinate (Flower) SAM
At this point an
Indeterminate (Florescence) SAM
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. Determinate Inflorescence Types
Present Indeterminate (Florescence) SAM
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. Determinate Inflorescence Types
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.
Simple Twice Compound
Compound Dichasiums/Cymes have a Different Kind of Compoundness
This kind is the same as seen in compound leaves

15. Determinate Inflorescence Types
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. Determinate Inflorescence Types
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. Determinate Inflorescence Types 2
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. Secondary Inflorescence Types
Rhipidiums arranged
as a Corymb
(often confused with a
Compound Corymb)
Panicle
Rhipidiums arranged
as a Raceme
(often confused with a
Compound 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

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

23. Compound and Multiple-compound
Rhipidium