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DAVID D. KECK
VII. SEED MORPHOLOGY
If seeds are small, taxonomic characters in them have often been
neglected in favor of other structures more readily available, and it is
often assumed that seeds are very constant in a group of plants. One
might suppose, for instance, that the seeds of Cruciferae would offer
relatively little to the taxonomist; but an intensive study of the characters
of these organs in 118 species of this difficult family in northeastern
North America shows that these seeds are sufficiently different to be
recognized at the species level, and that species can be keyed out on
these characters alone (Murley, 1951).
Seed characters may be very confusing, however, if only partially
understood. An interesting case is found in Halogeton glomeratus,
a
chenopodiaceous plant native to the Old World and becoming a pernicious weed in arid parts of the western United States. Two distinctly
different types of closely invested seed-like types of fruit may occur side
by side in the same inflorescence (Zappettini, 1953).
VIII. EMBRYOLOGY
Anatomical studies of the embryo in the seed have been of use in
elucidating the taxonomy of the tribes and subfamilies of the Gramineae
and in placing some aberrant genera in a more natural arrangement in
the phylogenetic system (Reeder, 1953). A more detailed example of
the use of gross internal features of seeds is the systematic analysis given
the seeds of 1287 genera by Martin (1946), with particular attention to
the relative size, shape, and position of the embryo and endosperm.
From this some new phylogenetic ideas evolved.
Embryology, as it applies to the study of male and female gametophytes and associated tissues and the development of the young sporophyte, offers data of value in classification particularly on the familial
and ordinal levels. Cave (1953) opens up this subject as it pertains to
classification on the generic level.
IX. PALEOBOTANY
The fossil record is of the utmost importance in gaining an understanding of evolution and in tracing the course of phylogenetic relationships.
Ordinarily the record contains so many gaps that it offers only suggestions as to the possible course of evolution, and the taxonomist working
with these data must use great caution in placing too much weight on the
hypotheses he must build around them. Paleobotanists in general are
orthodox taxonomists, and the rapid recent advances in the field under
the leadership of men such as Florin in Sweden, Thomas in England,
DAVID D. KECK
VII. SEED MORPHOLOGY
If seeds are small, taxonomic characters in them have often been
neglected in favor of other structures more readily available, and it is
often assumed that seeds are very constant in a group of plants. One
might suppose, for instance, that the seeds of Cruciferae would offer
relatively little to the taxonomist; but an intensive study of the characters
of these organs in 118 species of this difficult family in northeastern
North America shows that these seeds are sufficiently different to be
recognized at the species level, and that species can be keyed out on
these characters alone (Murley, 1951).
Seed characters may be very confusing, however, if only partially
understood. An interesting case is found in Halogeton glomeratus,
a
chenopodiaceous plant native to the Old World and becoming a pernicious weed in arid parts of the western United States. Two distinctly
different types of closely invested seed-like types of fruit may occur side
by side in the same inflorescence (Zappettini, 1953).
VIII. EMBRYOLOGY
Anatomical studies of the embryo in the seed have been of use in
elucidating the taxonomy of the tribes and subfamilies of the Gramineae
and in placing some aberrant genera in a more natural arrangement in
the phylogenetic system (Reeder, 1953). A more detailed example of
the use of gross internal features of seeds is the systematic analysis given
the seeds of 1287 genera by Martin (1946), with particular attention to
the relative size, shape, and position of the embryo and endosperm.
From this some new phylogenetic ideas evolved.
Embryology, as it applies to the study of male and female gametophytes and associated tissues and the development of the young sporophyte, offers data of value in classification particularly on the familial
and ordinal levels. Cave (1953) opens up this subject as it pertains to
classification on the generic level.
IX. PALEOBOTANY
The fossil record is of the utmost importance in gaining an understanding of evolution and in tracing the course of phylogenetic relationships.
Ordinarily the record contains so many gaps that it offers only suggestions as to the possible course of evolution, and the taxonomist working
with these data must use great caution in placing too much weight on the
hypotheses he must build around them. Paleobotanists in general are
orthodox taxonomists, and the rapid recent advances in the field under
the leadership of men such as Florin in Sweden, Thomas in England,