In botany , a micropyle (from Greek "little leaf") is defined as an appendix is supplied by a single unbranched nerve. 1 are leaves small, entire, destitute of petiole without vascularization or reduced venation a vein in some species does not exceed the base. Found for example in Selaginella and Lycopodium . In some stems dorsiventrales there anisofilia, meaning that in the same sector of the stem, leaves are formed different in size and shape on the top and sides. 2
Despite its mombre, the microphylls not always small. Those with the species of Isoetes , for example, grow to several centimeters in length, 3 and those of the extinct genus Lepidodendron reached over 20 cm .
Given this concept, psilotopsidas , lycophytes and equisetopsidas microphylls present because all currently existing species of these taxa have a single vascular bundle in each sheet.

In botany , a megafilo is a leaf flat, large and vascular. The megafilos of pteridophytes are called fronds . Large leaves are often made ??with highly developed venation. The growth of megafilos is due to the activity of a meristem apical persistent, whose activity, contrary to what happens in the spermatophytes - lasts long after the blade is deployed. Simple fronds present an elongated sheet, such as whole-in Ophioglossum - although it can be pinnatifid or pinnatisecta. In the fronds divided the sheet can be simply pinnate with the rachis as in Polypodium vulgare - or bi-or tripinnada with rachis rachises primary and secondary or tertiary, as in Polystichum filix-mas . The venation more frequent dichotomous venation fronds is open, but may be crosslinked, similar to that of the seed plants, as in the case of Ophioglossum .

The middle lamella is a layer of pectin for calcium and magnesium cementing together the cell walls of two plant cells adjacent. Is the first layer is deposited after cytokinesis , is often difficult to distinguish the middle lamella of the cell wall, especially if the cell develops a thick secondary wall.

When producing the embryogenesis , as the embryo grows during germination, it sends an outbreak (the radicle ), which will become the primary root to penetrate the soil. After leaving the radicle, the hypocotyl emerges bringing the apex of the plant (and usually also the seed coat) on the ground, carrying the embryonic leaves (called " cotyledon ") and" plumule ", which gives rise to the first leaves true. The hypocotyl is the first organ expansion of the young plant and develops into the stem of the plant.

The nectar is an aqueous solution more or less concentrated sugar , amino acids , ions minerals and flavorings. It is produced by the flowers as attractant and reward for the animals that perform the service of pollination (pollen involuntary transport to other flowers of the same or different plant).
Nectar is produced by glands at the base differentiated from stamens or petals , called nectaries, deposited in many cases in bags or spurs from the base of the corolla . This site requires agents pollinators to rub first with the stamens , which are loaded with pollen , and then with the stigma of second flowers, where some grains may be deposited.





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