A Key for the Determination of Microspecies of the Portulaca oleracea Aggregate

Published: April 4th, 2010 | Updated: 22/01/15

The present key includes all the microspecies determined to date, worldwide. It is hard to forecast if one microspecies or another will arrive and establish itself in this country.

1. Seeds bluish, covered (few or many, even in the same specimen) with wax; stellulae radially elongated; rays short (Fig. 11.1.15). P. nicaraguensis
1. Seeds not covered with wax → 2
2. Seed’s long diameter > 0.85 mm → 3
2. Seed’s long diameter < 0.85 mm → 12
3. Seed surface dull, at least some seeds have metallic sheen; surface with swellings with steep edges which may look like white dots, visible at a magnification of ×100 to ×1000 (Figs. 11.1.16, 11.1.17) → 4
3. Seed surface shiny; if covered with swellings, their edges terminate gradually as in mosquito-bites (Fig. 11.1.13d) → 5
4. Cells isodiametric with long rays, their center convex; look like a turtle shell. Plants of southwestern U.S.A. (Fig. 11.1.16). P. impolita
4. Cells elongated with short rays. Plants of the Canary Islands (Fig. 11.1.17). P. canariensis
5. (3) Seed surface covered with small papillae, of almost equal size (as in Figs. 11.1.12, 11.1.24) → 6
5. Seed surface covered with large tubercles (as in Figs. 11.1.9, 11.1.10) at the center of the cells or with papillae on the rays (Fig. 11.1.8), or with flat star-shaped cells and devoid of any protruberances (Fig. 11.1.5) → 7
6. Diameter of most seeds > 1.1 mm. An erect cultivated plant (Fig. 11.1.25). P. edulis
6. All seeds 0.85-1 mm diam. A prostrate spontaneous weed (Figs. 11.1.11, 11.1.18). P. rausii
7. (5) Surface stellulate, stellulae flat with neither tubercles nor papillae (Figs. 11.1.1, 11.1.5). [“Portulaca oleracea” P. oleracea]
7. At least one kind of tubercles or papillae is present on the lateral faces of the seeds → 8
8. Epidermal cells prominently stellulate, stellulae elongated with long rays and papillae at the end of many rays (Figs. 11.1.8, 11.1.30, 11.1.31). P. papillatostellulalta
8. Seeds tuberculate, tubercles at the central part of the cells and not on rays → 9
9. Most cells of the lateral seed face are elongated, with 3 (-2) tubercles close to each other (Fig. 11.1.10). P. trituberculata
9. Tubercles singular or in pairs at the center of isodiametric cells (as in Figs. 11.1.7a, 11.1.9) with long rays → 10
10. Tuberculate isodiametric cells with long rays present only at the periphery of the lateral face; the rest of the lateral cells elongated, flat and resembling the face of [“Portulaca oleracea” P. oleracea] and [“Portulaca nitida” P. nitida] (Fig. 11.1.5). P. sicula
10. Isodiametric tuberculate cells with long rays present on the entire lateral seed surface (Fig. 11.1.9) → 11
11. Seed diameter 0.85-1.0 mm; prostrate spontaneous plants. [“Portulaca cypria” P. cypria]
11. Seed diameter more than 1.1 mm; erect cultivar. . P. sativa
12. (2) Cells isodiametric with long rays, seed surface stellulate, stellulae flat with neither tubercles nor papillae (Figs. 11.1.22, 11.1.23). [“Portulaca nitida” P. nitida]
12. Cells elongated with short rays, often tuberculate or papillate → 13
13. Cells papillate → 14
13. Cells tuberculate, or tuberculate and papillate → 15
14. Papillae among the stellulae and actually emerging from the cell rays (Fig. 11.1.8). P. granulatostellulata
14. Seed surface covered with small papillae, almost equal in size; stellulae hardly seen (Fig. 11.1.12). P. zaffranii
15. Cells tuberculate-papillate; tubercles occur at the central part of the cell, papillae on a few of the rays. So far known from the Amazonas basin (Fig. 11.1.21). P. tuberculata
15. Tuberculate cells with long rays only at the periphery of the lateral face; the rest of the lateral cells elongated, flat and resemble the face of [“Portulaca oleracea” P. oleracea] and P. nitida. Recorded in 1932 from Timbuktu, Africa. P. africana

Fig. 11.1.15: Portulaca nicaraguensis – a., b., d forms with wax cover; c is a rare form with no wax.

Fig. 11.1.16: Seed surface of this microspecies has a metallic sheen.

Fig. 11.1.17: Portulaca canariensis – seed surface has metallic sheen.

Fig. 11.1.18: Portulaca rausii.

Fig. 11.1.19: Portulaca sicula.

Fig. 11.1.20: Portulaca sicula.

Fig. 11.1.21: Portulaca tuberculata.

Fig. 11.1.22: Portulaca nitida.

Fig. 11.1.23: Portulaca nitida.

Fig. 11.1.24: Portulaca sativa from a garden in Cyprus.

Forms of the cultivar P. sativa

The varius forms of Portulaca sativa share a vegetative characteristic – they are all erect as seen in Fig. 11.1.25. In the seed collections I studied, there were three forms of seeds with diameters exceeding 1.1 mm: seeds from Switzerland I saw in the Herbarium G in Geneve strongly resemble the seeds of [http://flora.huji.ac.il/browse.asp?lang=en&action=specie&specie=PORCYP P. cypria] (as in Fig. 11.1.26). Seeds of P. sativa collected in Cyprus (Fig. 11.1.25) resemble seed surfaces of P. rausii (Fig. 11.1.11, 11.1.18) or of P. zaffranii (as in Fig. 11.1.12). P. sativa was found in archaeological excavations from the 14th-15th century C.E., near Ferrara, Emilia Romagna, Italy (Figs. 11.1.27, 11.1.28; Bossi et al. 2009). Each seed carries a composite of these two forms. Could it be a kind of parent form (Fig. 11.1.28) that split up into the two types?!

Fig. 11.1.25: Georgios Hadjikiryakou photographs Portulaca sativa in a garden in Cyprus.

Fig. 11.1.26: Portulaca sativa from Switzerland.

Fig. 11.1.27: Portulaca sativa from an archaeological site near Ferrara, Italy.

Fig. 11.1.28: Cell mixture in a close-up of photograph 11.1.27.

Fig. 11.1.29: Portulaca sativa from Cyprus.

Long diameter of the seed 0.906 mm; stellate cells with occasional papillae

Fig. 11.1.30: Portulaca papillatostellulata.

Fig. 11.1.31: Portulaca papillatostellulata.