Pollen tube tubes. The presence of multiple grains of pollen has been observed to stimulate quicker pollen tube growth in some plants. The vegetative cell then produces the pollen tube, a tubular protrusion from the pollen grain, which carries the sperm cells within its cytoplasm. The sperm cells are the male gametes that will join with the egg cell and the central cell in double fertilization. The germinated pollen tube must then drill its way through the nutrient-rich style and curl to the bottom of the ovary to reach the ovule. Once the pollen tube reaches an ovule, it bursts to deliver
Ear (botany) Ear (botany) An ear is the grain-bearing tip part of the stem of a cereal plant, such as wheat or maize. It can also refer to "a prominent lobe in some leaves". The ear is a spike, consisting of a central stem on which tightly packed rows of flowers grow. These develop into fruits containing the edible seeds. In corn, it is protected by leaves called husks. In some species (including wheat), unripe ears contribute significantly to photosynthesis, in addition to the leaves lower down the plant. A parasite known as "Anguina tritici" (Ear Cockle) specifically affects the ears on