The Collaborative International Dictionary of English v.0.48:

Spermatophyta \Sper`ma*toph"y*ta\, n. pl. [NL.; spermato- + Gr.
   ? plant.] (Bot.)
   A phylum embracing the highest plants, or those that produce
   seeds; the seed plants, or flowering plants. They form the
   most numerous group, including over 120,000 species. In
   general, the group is characterized by the marked development
   of the sporophyte, with great differentiation of its parts
   (root, stem, leaves, flowers, etc.); by the extreme reduction
   of the gametophyte; and by the development of seeds. All the
   Spermatophyta are heterosporous; fertilization of the egg
   cell is either through a

   pollen tube emitted by the microspore or (in a few
      gymnosperms) by spermatozoids.

   Note: The phrase "flowering plants" is less distinctive than
         "seed plants," since the conifers, grasses, sedges,
         oaks, etc., do not produce flowers in the popular
         sense. For this reason the terms Anthrophyta,
         Phaenogamia, and Panerogamia have been superseded
         as names of the phylum by Spermatophyta.
         [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Pollen \Pol"len\, n. [L. pollen fine flour, fine dust; cf. Gr.
   ?]
   1. Fine bran or flour. [Obs.] --Bailey.
      [1913 Webster]

   2. (Bot.) The fecundating dustlike cells of the anthers of
      flowers. See Flower, and Illust. of Filament.
      [1913 Webster]

   Pollen grain (Bot.), a particle or call of pollen.

   Pollen mass, a pollinium. --Gray.

   Pollen sac, a compartment of an anther containing pollen,
      -- usually there are four in each anther.

   Pollen tube, a slender tube which issues from the pollen
      grain on its contact with the stigma, which it penetrates,
      thus conveying, it is supposed, the fecundating matter of
      the grain to the ovule.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pollen tube
    n 1: (botany) a slender tubular outgrowth from a pollen grain
         when deposited on the stigma for a flower; it penetrates
         the style and conveys the male gametes to the ovule