For ease of use, only the most striking diagnostic features are given here. It is particularly helpful to refer to the classification at the Sub-section and Series levels. A few of the Series contain the majority of the species, especially those of horticultural interest. These are Robustae, Simplicifoliae, Grandes and Aculeatae.
The figures in parentheses denote the photographs at the bottom of the page. These have been chosen to illustrate the botanical features mentioned.
In Taylor's monograph, some species listed here are either not referred to as distinct species or for one of several reasons (e.g. new to science), not listed at all. These are MM. sherriffii, rudis, tibetica, pinnatifolia, simikotensis, pseudovenusta and sino-maculata. In the classification outlined here, not all species are cited, but only those most likely to be encountered. Note that well-known M. villosa is omitted as this has been removed by Chris Grey-Wilson to its former genus, Cathcartia.
- Subgenus - Discogyne Five species, MM. discigera, pinnatifolia, simikotensis, tibetica and torquata. Flat disc occurs on top of the ovary with a short stigma on top of this (1). M. discigera only occasionally brought to flowering in cultivation. (See also Disgoyne)
- Subgenus - Eumecononpsis No flat disc (2)
- Section - Cambricae One species only, M cambrica (Welsh poppy). Only species which is not Asian. Possibly will have a new generic name in the revision of the genus which is currently under way. Very easy in cultivation - almost a weed for many people!
- Section - Eucathcartia Only two species. The one in cultivation is M. chelidonifolia.
- Section - Polychaetia Polycarpic or monocarpic perennials
- Subsection Eupolychaetia Evergreen monocarpic perennials, with an over-wintering rosette of leaves.
- Series Superbae Leaves with finely toothed (serrate) margins (3) and clothed with silky hairs. Two species, MM. superba, regia, the former in cultivation, the latter has been in the past, but not at present.
- Series Robustae Leaves with variously lobed margins (4) and covered with bristly hairs. MM.napaulensis, staintonii, wallichii, paniculata, wilsoni, dhwojii, gracilipes. Many of them are in cultivation.
- Subsection Cumminsia Deciduous monocarpic or polycarpic perennials, lacking an evergreen rosette of over-wintering leaves.
- Series Grandes The inflorescence comprises a flowering stem (peduncle) which is leafy (5), with several of the uppermost leaves (bracts) aggregated in a "false whorl" around the top of the stem, above which the flowers, each borne on a pedicel, arise (6). Some pedicelled flowers may also occur in the axils of the leaves below the "false whorl". MM. integrifolia, sherriffii pseudointegrifolia, baileyi, betonicifolia, grandis.
Monocarpic or polycarpic. In cultivation. True M. grandis is still rare in cultivation.
- Series Simplicifoliae Flowers borne on scapes (leafless flowering stems arising directly from the ground - i.e. there is no peduncle) (7)
Monocarpic or polycarpic. MM. simplicifoliae, punicea, quintuplinervia. In cultivation.
- Series Aculeatae Comprises a large number of monocarpic perennials. Flowers are either scapose (8) or are borne on a leafy inflorescence (9). MM. aculeata, forrestii, henrici, horridula, lancifolia, latifolia, pseudovenusta, prattii, rudis, sino-maculata, speciosa. Some in cultivation, some not.
- Series Delavayanae One species only, M delavayi. Small polycarpic perennial with a few entire leaves. In cultivation, but not the easiest.
- Series Bellae One species only, M. bella. Small polycarpic perennial often with finely divided leaves. Has proved intractable in cultivation.
- Series Primulinae Several species, MM. florindae, lyrata, primulina and argemonantha. The flowers are in the axils of the upper leaves, or, when there is only one flower, the flowering stem bears leaves.. Monocarpic perennial. None of these is in cultivation.