Perisperm


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Related to Perisperm: funiculus, pericarp, nucellus

perisperm

[′per·ə‚spərm]
(botany)
In a seed, the nutritive tissue that is derived from the nucellus and deposited on the outside of the embryo sac.

Perisperm

 

reserve nutritive tissue in a seed used by the embryo in sprouting. Functionally, the perisperm is similar to the endosperm. However, it forms from the nucellus and has a diploid, and not triploid, chromosomal set. In addition, it lacks proteins and contains chiefly starch and, less commonly, fat. Perisperm characterizes plants of the families Caryophyllaceae, and Zingiberaceae, Piperaceae, and Nymphaeaceae. Among gymnosperms, it is found in Gneticae and Taxaceae. The perisperm constitutes all or part of the reserve tissue. When it forms only part of the seed’s reserve, it develops parallel with the endosperm.

References in periodicals archive ?
In Lomandraceae neither dermal nor central conducting regions contain storage material, so this is presumably not a perisperm, as in the case of the enlarged dermal nucellus cells of Acorus (see below).
Tissues that result from the later proliferation of the proximal region of the nucellus, such as in Capsella (Schulz & Jensen, 1971), where this region proliferates around the time of fertilisation, are not postaments but probably a type of perisperm (see below).
Seed storage tissues derived from the nucellus are termed perisperm, but perisperm may develop even before anthesis.
Arnott (1962) recorded a perisperm entirely surrounding the embryo in seeds of Yucca (Agavaceae), rather similar to that described for Eriospermum (Lu, 1985).
Dahlgren and Clifford (1982, and references therein) regarded Zingiberales as "the main monocotyledonous group with perisperm." Perisperm is sometimes entirely compressed in the mature seed, only the cell walls remaining (e.g., in Musa: Graven et al., 1996).
This develops into a distinct region of thin-walled cells immediately adjacent to the megagametophyte; it is possibly a storage tissue, and therefore perisperm. The proximal part of the nucellus is differentiated into two distinct regions, both with a possible nutritive role (Fig.
Since this is entirely nucellar in origin, this tissue is probably a perisperm, not a chalazosperm (Rudall, 1994).