Classifying the arrangement of flowers is rather specialised, resulting in a great many differing categories that, to the layman, are very hard to interpret or differentiate between in the real world. So the author has greatly simplified the available categories to more closely relate with the laymans' interpretation of the arrangement of flowers. For instance, Panicle is not an official designation, and its use by biologists is discouraged, but to the layman it has a fairly well defined understanding, so is used here. But this category excludes the florets and rays in composite dandelion-type flowers.
This is a catch-all category, which includes all those flower types under the headings CATKINS, GLOBED, UMBEL, SPIKED and PANICLE. It even includes those for which individual flowers are so small and compacted that they cannot be discerned and for which there is no other category, such as those in the spadix of Arums and those in the inflorescence atop Bulrushes. Example of plants with clustered flowers would be the Clovers (which would also be categorized as globed), Hydrangea (which would also be categorised as 'umbel'), etc.
Globed or Globular flowers include Orange-Ball-Tree, the Globe-Thistles, Round-Headed Leek, Strawberry Tree, Wild Leek, Garden Leek, Star-of-Persia, Onion, Chives and perhaps Globeflower although that is a single globe-shaped flower rather than a cluster of flowers in a spherical globe. Included in this category are any flower-heads that are spherical over at least 3π steradians (there being 4π steradians in a sphere).
Catkins are usually long pendant and compact flowers of (usually) trees which are in the form of a long thin dangling thing which lack petals. [Your Author has also possibly taken a liberty in also categorising as 'catkins' long pendant flowers such as those on Nettle, Bog Myrtle, Butterfly-bush, Annual Mercury and Sedges because they also droop down in a long thin dangly thing - but these do have petals]. Those catkins on trees lack petals - there is no biological need to attract the attention of flying insects with the aid of showy petals when the catkins are fertilised by wind-blown pollen rather than pollen brought to the flowers by insects. Hazel and Alder catkins (the long ones) are the male flowers, the much shorter and stiffer danglers are the female flowers.
Most usually characterised by the Umbellifers (Apiaceae, but umbels are not exclusive to the umbellifers; indeed, some umbellifers lack umbels. For instance, the flowers of Elder form an umbel, but Elder is not an umbellifer. An umbel is a flattish cluster of flowers facing upwards, and may be a simple umbel, or compound or triple-compound where the umbel is formed on fractally branched stems.
Whorls of flowers of roughly the same size repeated up the stem.
In this tomb, a spike is a tower of flowers, either parallel sided, or tapered (as shown).
This category encompasses both Racemes and Panicles, which are stems, possibly horizontal or drooping, which are covered in flowers, either themselves on smaller branches (compound panicles) or not.
INDIVIDUAL FLOWER FORM
In this tome 'trumpet' shaped flowers are daffodil-like.
In this tome 'bell' shaped flowers dangle earthwards and are more or less spherical with an opening at the farther point (which may or may not have shallow petals curving outwards). For instance like
In this tome 'fused' petals are those which might be bindweed-like (which have 5 'petals' but without any nicks in them). Or it might be where there are actually more 'petals' to the flower than those which you can count; the others being fused together os one.
Any petals that are frayed or have a fringe at the periphery. This category does not include those petals which appear to have been cut by pinking shears around the extreme edges, as do many members of the Dandelion & Daisy Family such as the Dandelions, Hawkweeds, Hawkbeards, Hawbits, or Sow-Thistles etc.
'Tubular' flowers are tubular with only tiny nicks at the end between any 'petals' - such as those on Comfrey, Solomon's-seals, Red-hot-pokers, and Navelwort.
Some flowers have a tapered tubular spur at the rear that is enclosed, and usually contains nectar to attract and nourish visiting insects. The spur can be hidden (some Orchids) or conspicuous (some Balsams), and very long (Greater Butterfly-Orchid) to a very short 2mm (Frog Orchid) or stubbily short (Monkey Orchid). Species of Dicentra (Bleeding Hearts) have 2 spurs each flower.