Portulaca oleracea L.

Algeria: Portulaca oleracea germinates in late winter and throughout spring; flowering takes place from May to September.

Mayotte: Portulaca oleracea (P. granulatostellulata) flowers from October to June and fruits from November to July.

Portulaca oleracea is an anemochorous and hydrochorous species.

Portulaca oleracea can be very easily confused with Portulaca granulatostellulata (Poelin.) Ricceri & Arrigoni. These two species are vegetatively and floristically similar and differ only in the ornamentation of their seed coat
The seeds of P. oleracea have a tegument marked with star-shaped cells, flat and without emergences.
The seeds of P. granulatostellulata have a tegument with star-shaped cells with papillae emerging from the rays.

Portulaca granulatostellulata (= Portulaca oleracea subsp. granulatostellulata (Poelln.) Danin & H.G.Baker) occurs in Western Europe, Northern India, Central America, Northern and Eastern Africa, Comoros and Reunion. It has been introduced in the Caribbean and in the Pacific islands (Hawaii, Tuamotu).

Do to the difficulty to distinguish these two species and their similar behavior, we shall consider all under the name Portulaca oleracea.

Portulaca oleracea is a C4 species.

Algeria: Portulaca oleracea is a thermophilic, sun-loving, hygrophilic (but drought tolerant in the adult stage), and nitrophilic species, very common in the different annual irrigated crops (notably summer irrigation market gardening and nurseries) and perennial crops (notably citrus groves) of the country. Preference for sandy to loamy, moist and nitrogen-rich soils, as well as alluvial soils along rivers.
Northern Cameroon: Portulaca oleracea is a species which does not have significant climate preference provided that the temperature is between 15 and 35 ° C. In addition, it is insensitive to day length and can bloom with a photoperiod of 4 to 24 hours. It grows on different types of soil, but prefers rich, moist soil, sandy clay or sandy loam as the alluvium along rivers. It is a sun-loving species that grows in open places.
Comoros: Ruderal species that prefers sunny and warm places. It is common on the three islands, especially in areas of low and middle altitude, up to 800 m.
French Guiana: Common species of well-drained, ruderal, non-flooded areas.
Madagascar: Ruderal and weed common in rainfed cultivation.
Mauritius: Weed very common in cultivated fields and fallow land in the lower part of the island.
Mayotte: Portulaca oleracea (P. granulatostellulata) is a cryptogenic species quite common in littoral zones like islets and points, rocky cliffs and stabilized sands. It is also a species of the urbanized environments and a weed of crops.
New Caledonia: Considered as one of the major adventitious crops it is mostly present on southern red soils. However, it believes in a wide variety of clay and sandy soils. It tolerates sunny environments, quite dry, like back beaches.
Reunion: The species particularly love the sunny and warm places. It is common on the north and west coasts, as well as at medium altitude, up to Cilaos. It grows on different soils, but prefers rich, moist soil, sandy clay or sandy loam.
Seychelles: This species is observed in all regions from 0 to 300 meters, but prefers dry, sunny areas near the coast.

Global harmfulness
 
Portulaca oleracea is a particularly important weed in irrigated crops and offseason vegetable crops..
 
Local harmfulness
 
Algeria: Portulaca oleracea is a major "weed". It is one of the most harmful species of field crops because it can colonise practically all ecological environments (very frequent species), and its great adaptation to the agricultural environment gives it a very high potential for invading (very high seed production) plots (very abundant species). It is very harmful because of its rapid growth, its great capacity to pump water from the soil, its greed for mineral elements, its covering development which filters the light at the surface of the soil thus preventing the emergence of other seedlings, the high number of seeds produced (even after removal of the plant) which are dormant and viable for a long time in the soil, and its capacity to multiply by cuttings
South Africa: Portulaca oleracea is present throughout the country. Declared weed, competitive overlooked cultures.
Benin: rare but abundant when present.
Burkina Faso: Frequent and scarce.
Northern Cameroon: It remains a minor weed in dry crops like cotton, maize, groundnuts and sorghum, although it is present in nearly 20% of the plots. In these cultures, it is never abundant.
Comoros: A weed common in cassava and vegetable crops.
Ivory Coast: Frequent and scarce.
Ghana: Rare and scarce.
French Guiana: Quite common weed in vegetable plots and can be occasionally abundant.
Kenya: Frequent and scarce.
Madagascar: low frequency species and scarce except in smoked fields near the villages (maize) or in the plains or depression in fertile soil (cotton, vegetables).
Mauritius: It is not present in crops.
Mali: Frequent and scarce.
Mayotte: Portulaca oleracea (P. granulatostellulata) is a fairly frequent weed, present in 10% of cultivated plots, especially in vegetable crops.
Nigeria: Frequent and scarce.
New Caledonia: Portulaca oleracea does not constitute a major weed of pastures. It is even consumable by livestock. However its toxicity implies to monitor its development on pastures to avoid any overconsumption.
Uganda: Rare but abundant when present.
Reunion: P. oleracea is present in 20% of cultivated plots. This is a particularly important weed in irrigated and vegetables cultivations. In the sugar cane fields, it accompanies only very young canes because of its light requirement. It quickly becomes abundant in vegetables and lens.
Senegal: Rare and scarce.
Seychelles: occasional weed of many cultures, especially in gardening and ornamental crops. It is a serious competitor, especially for young crops.
Tanzania: Frequent and scarce.

Herbarium pictures ReCOLNAT: https://explore.recolnat.org/search/botanique/simplequery=Portulaca%2520oleracea