During which stage do leaves remain tightly rolled to form a spike?

The spike stage is characterized by the tight rolling of leaves, which is a distinctive feature during this developmental phase of certain grasses and crops. At this stage, the new leaves are still developing and have not yet fully expanded, remaining in a tightly rolled form. This rolling is important for protection against environmental stresses and helps in water retention.

In contrast, the flag stage refers to the emergence of the uppermost leaf, which is usually identifiable and can be recognized by its full expansion. The jointing stage occurs after the spike stage and involves the elongation of stems, leading to the formation of nodes. Summer annuals are a category of plants based on their lifecycle rather than a specific growth stage. Therefore, the identification of the spike stage as the period when leaves are tightly rolled correctly captures the unique morphological characteristics of plants at that time.