Alternation of Generation by Welhilum Hofmister and Phylogentic Trend by Welhilum Echiler. Phylogenetic trend refers to the evolutionary connection between different groups of organisms - how they are related in terms of their origin and development. Also known as the "vascular-terrestrial" model proposed by Wilhelm Hofmeister in 1851. Describes the life cycle of plants that have distinct haploid (n) and diploid (2n) stages, such as ferns and flowering plants.

1.  Submitted To:
MR Abdullah Farooq
 Submitted By:
Hassan Tariq

2. 𝕴𝖓𝖙𝖗𝖔𝖉𝖚𝖈𝖙𝖎𝖔𝖓:
 Wilhelm Hofmeister (1824 –1877) was
a German Biologist and Botanist.
 He started teaching at University of Heidelberg in 1851
 Discover the concept of "cell plate" during cell division, which is
observed in the red alga.
 Made several important contributions to the field of botany,
study of cell division and differentiation in plants and the Discovery of the alternation of
generations in plants and also proposed the idea of meristem cells,
Systematic classification of plants and Phylogenetics
 Wilhelm Hofmeister did not receive any Nobel Prizes during his lifetime.

3. 𝕳𝖔𝖋𝖒𝖊𝖎𝖘𝖙𝖊𝖗 𝕸𝖔𝖉𝖊𝖑 𝕺𝖋 𝕬𝖑𝖙𝖊𝖗𝖓𝖆𝖙𝖎𝖔𝖓 𝕺𝖋 𝕲𝖊𝖓𝖊𝖗𝖆𝖙𝖎𝖔𝖓 :
 Also known as the "vascular-terrestrial" model proposed by Wilhelm Hofmeister in 1851.
 Describes the life cycle of plants that have distinct haploid (n) and diploid (2n) stages, such
as ferns and flowering plants.
 According to Hofmeister's model, these plants have two distinct types of spores – the haploid
spores (n) produced by the sporophyte generation (2n), and the diploid spores (2n) produced
by the gametophyte generation (n).The haploid spores develop into gametophyte generation,
which produces haploid gametes (either eggs or sperm) through mitosis. The gametes then
fuse to form a diploid zygote (2n), which develops into the sporophyte generation through
mitosis.
 Sporophyte generation produces diploid spores(2n) through meiosis, and cycle repeats itself.
 Sporophyte generation is the dominant generation, while the gametophyte generation is
dependent on the sporophyte.

5. 𝖈𝖔𝖓𝖙𝖗𝖎𝖇𝖚𝖙𝖎𝖔𝖓𝖘 :
 Divisions of plant life: He divided plant development into several distinct stages, including the
primary division of the cell, growth of the embryo, differentiation of the tissue.
 Cell division and differentiation: He research on cell division and differentiation in plants
to the understands the cellular processes that occur during plant growth and development.
He discovered the "cell plate" in the red alga, which is a precursor to the cell wall that
separates two daughter cells after cell division.
 Systematic classification of plants: He was involved in the systematic classification of plants,
which aimed to organize plants into distinct groups based on their characteristics. His work
become basis for later classification systems, such as proposed systems of Engler and Prantl.
 Alternation of generations: He was one of the first scientists to study the phenomenon of
alternation of generations which helped him to explain the pattern of sexual and asexual
reproduction in plants.

6. 𝕽𝖊𝖏𝖊𝖈𝖙𝖎𝖔𝖓𝖘:
 Hofmeister's work that has been the subject of some
criticism is his theory of the "growing-point theory,"
which he proposed to explain the meristem. In this
theory, He suggested that the apex of the meristem
contains a "growing point," which controls the direction
of growth and differentiation of the surrounding cells.
 This theory was widely accepted in His time.But Today,
scientists recognize that the meristem is a highly dynamic
and complex structure that is influenced by many factors,
including hormonal signals, environmental cues, and
genetic factors.

7. 𝕴𝖓𝖙𝖗𝖔𝖉𝖚𝖈𝖙𝖎𝖔𝖓:
 August Wilhelm Eichler (1839 – 2 March 1887) was a German
botanist.
 In 1865, Eichler start his work at the Royal Herbarium in Berlin,
on plant morphology and classification.
 "Blüthendiagramme" (1875) which proposed a standardized
system for representing the structure of flowers, and
"Blüthensekunde" (1878 and 1883) which focused on the
organs and structures of flowers in detail.
 "Sympetale Blüthendiagramme" (1883) This work focused on
the sympetalous flowering plants, which are plants in which the
petals are fused together into a single structure.
 He contributes to plant anatomy, embryology, and paleobotany.
He also develop the "Eichlerian system" of classification.

8. 𝕻𝖔𝖑𝖞𝖌𝖊𝖓𝖊𝖙𝖎𝖈 𝕿𝖗𝖊𝖓𝖉 𝖎𝖓 𝕻𝖑𝖆𝖓𝖙 𝕮𝖑𝖆𝖘𝖘𝖎𝖋𝖎𝖈𝖆𝖙𝖎𝖔𝖓 :
 Phylogenetic trend refers to the evolutionary connection between different groups of
organisms - how they are related in terms of their origin and development.
 It can be studied in a number of ways, including observation of the fossil record or by
analyzing the structural, genetic, and molecular characteristics of organisms. By examining
the similarities and differences between organisms at a molecular level.
 Phylogenetic system was based on dividing the plant kingdom into plants with concealed
reproductive organs such as Cryptogamae (hidden reproduction) and Phanerogamae
(visible reproduction).
 By understanding the evolutionary relationships between different groups of organisms,
we can create more accurate and meaningful systematics.

9. 𝖈𝖔𝖓𝖙𝖗𝖎𝖇𝖚𝖙𝖎𝖔𝖓𝖘 :
 Floral Morphology: Most influential contributions was his work on the structure and
classification of flowers. He developed a system for showing the structure of flowers that
is still used today, known as the "Eichlerian diagram.“
 Classification of plants: He proposed “Eichlerian system of classification” which grouped
plants based on their morphological characteristics.He also played an important role in
the field of paleobotany, which involves the study of fossil plants.
 Plant anatomy: Eichler made significant contributions to the understanding of plant
anatomy, publishing research on embryology, fruit development.
 Paleobotany: Eichler also studythrancient plants, and helped to build one of the world's
most comprehensive collections of fossil plant specimens while working at the Museum
of Berlin.

10. 𝕯𝖎𝖘𝖆𝖉𝖛𝖆𝖓𝖙𝖆𝖌𝖊𝖘 𝖔𝖋 𝖕𝖍𝖞𝖑
𝖔𝖌𝖊𝖓𝖊𝖙𝖎𝖈 𝖈𝖑𝖆𝖘𝖘𝖎𝖋𝖎𝖈𝖆𝖙𝖎𝖔𝖓:
 In phylogenetic
classification, closely
related species do not
always appear to be overly
uniform.
 While the groups that are
not closely related but
evolved under similar
conditions may look more
similar to each other.
 Knowing the evolutionary
history of all the species is
not possible.