<span>In plant anatomy, sieve tube elements, also called sieve tube members, are a specialised type of elongated cell in the phloem tissue
of flowering plants. The ends of these cells are connected with other
sieve tube members, and together they constitute the sieve tube.
Hope this help!
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Speciation can be difficult to observe in nature, but the it is hypothesized that the following occurs in a allopatric speciation's intermediate stage:
(1) closely related species are differentiated through geographic variation (2) then there's reduced fertility in one a geographic race of the species (3) and in the geographic race of subspecies that are to become species.
saliva in mouth
pepsin,hcl,and mucus are responsible for digestion of food
They don't have ovaries !!
so they don't turn into fruits and thus seeds are naked !!
