Dandelions are the earliest spring flowers. Though the plants are used as food and for medicinal use, it is generally considered as a weed. They compete with the agriculture crops by lowering food production (McPeek and Wang, 2007). In the suburban homes, dandelions impact the aesthetics of the lawns and gardens.
Dandelions were introduced in the Americas from Europe by the early European settlers (Iaffaldano et al. 2017). They have since spread all over the continent. The plants are highly successful in adapting to different conditions and environments. In this paper we demonstrated that the dandelion uses different strategies to adapt to the suburban conditions.
Our study areas were confined to the counties west of Philadelphia, Pennsylvania. Urbanization has reduced areas for the habitat of dandelions. The taller dandelions (“wild”) are seen in nature reserves, wastelands, or peripheral areas of the suburbs (“wild areas”) with few human activities. The dandelions of the wild areas are taller with larger flowers, flower stalks, and leaves. The mean angle of the dandelion’s flower stalks of the wild areas was calculated to be around 700, and the angle of the seed head stalks was calculated to be 900 (Fig. 6).
In the suburbs, the dandelions occupy lawns and gardens. They grow in spaces between the lawn grasses. The suburban dandelions have smaller leaves, short flower stalks that are at an angle of 300 or lesser, smaller flowers that grows parallel to the lawn grass and early blooming; features that can escape mowing. However, the seed stalks were significantly longer than the flower stalks to aid in wind dispersal (Fig. 7).
In the suburbs, the dandelion blooms, set seeds and disperses the seeds usually before the first lawn mowing. The lawns are mowed regularly when the grass grows during mid-spring. The seed head stalks elongate before the mowing, or after the first mowing. The seed head stalks of the dandelions in the wild, or in the lawn is 900. The seeds of the dandelions are dispersed by wind. Wind can transport the seeds to long distances (Cummins et al. 2018). A taller seed head stalk can influence the transport of the seeds. Rarely have we observed short seed head stalks in dandelions. Seeds from the short seed head stalks fall in the vicinity of the dandelion plants thereby impacting its germination (Fig. 8). Hence, we speculate that longer seed head stalks are an adaptation favoring transport of the seeds to long distances and its survival.
Though the dandelions in the lawn of the suburbs are shorter, those plants growing at the periphery of the lawns, with no human activities are comparable to the plants as seen in the wild with longer flower stalks and larger leaves. Thus, a favorable environment elicits larger vegetative growth of the plants.
Overall, our studies demonstrate that the dandelions have adapted to human environments. The habit of dandelion in the suburbs is an example of Anthroprokaresta (human induced change; Greek; Anthropos, human; Prokalesei, induce; Resta, change). Dandelion with small leaves, short floral stalks with an angle of 300 or lower, that can escape mowing, and early blooming and seed dispersal gives the plant an edge for its survival. The vertical elongation of dandelions seed head stalks helps the wind dispersal of the seeds to large distances.
This paper demonstrates significant decrease in the size of dandelions in playgrounds. Based on the study, we could speculate that large numbers of people visiting natural reserves and national parks could influence the size of plants. Regulating the number of visitors visiting national parks could positively influence the plant morphology and plant health.