Weed evolution and community structure - Ecological Management of Agricultural Weeds - page 457

Table 10.1. Weeds present in interglacial, full glacial, and late glacial deposits in
Britain a

Species Interglacial Full glacial Late glacial

Aethusa cynapium M

Carduus nutans M (M)

Chenopodium album M M

Cirsium vulgare M

Heracleum sphondylium M

Pastinaca sativa M (P) P

Plantago ( major or media ) (P) P P

Valerianella (3 species) M

Artemisia spp. (P) (P) (P)

Linum catharticum P

Trifolium spp. (P)

Barbarea vulgaris M

Centaurea cyanus P

Centaurea nigra P

Cerastium vulgatum M

Daucus carota M

Galeopsis tetrahit M

Galium aparine M

Linaria vulgaris M

Polygonum aviculare M

Rumex acetosa M

Rumex crispus M

Sonchus arvensis M

Taraxacum officinale M

Urtica spp. (P)

Notes:
a M indicates macroscopic remains (chiefly seeds or fruits) and P indicates pollen.Where material
from a period was only identified to genus,the entry is given in parentheses.
Source : Summarized from Godwin (1960).

and Polygonum aviculare (Wasylikowa et al ., 1985). Iversen (1941) and Godwin
(1960) similarly noted the presence of weed pollen in association with the
arrival of agriculture in Denmark and Britain. The presence of plant remains
from interglacial and glacial deposits in Britain indicates that many weed
species were already present when agriculture first arrived (Table 10.1)
(Godwin, 1960). Thus, as agriculture has spread across the globe, species
native to each region have been added to the total pool of weeds.
This process continues as agriculture penetrates the remaining non-agri-
cultural regions of the world. For example, Conn & DeLapp (1983) noted that
several native species could invade and persist in grain fields recently estab-
lished in the Alaskan interior.Similarly,the forest gap species Solanum crinitum