60
DAVID D. KECK
for example, can be readily distinguished by their wood anatomy, each
one of the common classification schemes for the family could be supported from the evidence at hand from this source, namely, one family
undivided, one family with three subfamilies, or two families (Mimosaceae and Papilionaceae), the latter subdivided into two subfamilies
(Reinders-Gouwentak, 1955).
Detailed studies of the secondary xylem have been very helpful in
solving problems of relationship at the generic level also. In the taxonomically "difficult" Icacinaceae this feature proved very useful in
helping to determine whether several genera tentatively assigned to it
should be included or excluded from the family (Bailey and Howard,
1941). Help came from another unusual source—pollen morphology
(Dahl, 1952, 1955). Studies of the secondary xylem and pollen grains
were also linked to corroborate a taxonomic segregation of the Rhus
complex in the Anacardiaceae that had been proposed on conventional
taxonomic grounds (Heimsch, 1940).
Data obtained from a comparative morphological study of the inflorescences in the Juglandaceae were used to interpret generic relationships within the family (Manning, 1938), and with one exception the
conclusions arrived at were strikingly confirmed by a study of the xylem
anatomy (Heimsch and Wetmore, 1939). In general, anatomical data
may be of considerable applicability to taxonomy from the generic level
upwards, but of inconsequential value for intrageneric interpretations.
Floral anatomy has been used extensively in the drawing up of phylogenetic schemes, and it has proved to be a valuable taxonomic tool for
chiseling out some of the broader outlines of natural relationships, as
for example, relationships on the family level (Dawson, 1936; Smith and
Smith, 1943; Copeland, 1938, 1953, 1954a; and Copeland and Doyel,
1940). Certainly it is of much use in the solution of morphological problems (Puri, 1951). As in the case of other tools, however, its greatest
value comes when it is employed in conjunction with other lines of evidence, whether from comparative morphology in the broad sense or
otherwise. When used in this way its importance to taxonomic conclusions is brought out in a well-documented report by Eames (1951) that
takes strong exception to a radically new systematic arrangement of seed
plant families based on morphology of organs alone (Lam, 1948a, b).
Eames points out many examples of failure in a system of classification
that relies too wholly on a limited line of evidence.
The vascular anatomy of the flower offers a more sensitive gauge for
measuring generic relationships than does wood anatomy. Its usefulness
DAVID D. KECK
for example, can be readily distinguished by their wood anatomy, each
one of the common classification schemes for the family could be supported from the evidence at hand from this source, namely, one family
undivided, one family with three subfamilies, or two families (Mimosaceae and Papilionaceae), the latter subdivided into two subfamilies
(Reinders-Gouwentak, 1955).
Detailed studies of the secondary xylem have been very helpful in
solving problems of relationship at the generic level also. In the taxonomically "difficult" Icacinaceae this feature proved very useful in
helping to determine whether several genera tentatively assigned to it
should be included or excluded from the family (Bailey and Howard,
1941). Help came from another unusual source—pollen morphology
(Dahl, 1952, 1955). Studies of the secondary xylem and pollen grains
were also linked to corroborate a taxonomic segregation of the Rhus
complex in the Anacardiaceae that had been proposed on conventional
taxonomic grounds (Heimsch, 1940).
Data obtained from a comparative morphological study of the inflorescences in the Juglandaceae were used to interpret generic relationships within the family (Manning, 1938), and with one exception the
conclusions arrived at were strikingly confirmed by a study of the xylem
anatomy (Heimsch and Wetmore, 1939). In general, anatomical data
may be of considerable applicability to taxonomy from the generic level
upwards, but of inconsequential value for intrageneric interpretations.
Floral anatomy has been used extensively in the drawing up of phylogenetic schemes, and it has proved to be a valuable taxonomic tool for
chiseling out some of the broader outlines of natural relationships, as
for example, relationships on the family level (Dawson, 1936; Smith and
Smith, 1943; Copeland, 1938, 1953, 1954a; and Copeland and Doyel,
1940). Certainly it is of much use in the solution of morphological problems (Puri, 1951). As in the case of other tools, however, its greatest
value comes when it is employed in conjunction with other lines of evidence, whether from comparative morphology in the broad sense or
otherwise. When used in this way its importance to taxonomic conclusions is brought out in a well-documented report by Eames (1951) that
takes strong exception to a radically new systematic arrangement of seed
plant families based on morphology of organs alone (Lam, 1948a, b).
Eames points out many examples of failure in a system of classification
that relies too wholly on a limited line of evidence.
The vascular anatomy of the flower offers a more sensitive gauge for
measuring generic relationships than does wood anatomy. Its usefulness