Integrative Biology 335:
Systematics of Plants
Rosaceae

Announcements:
... just in case you missed Friday's announcements
So far, you have had 10 lecture quizzes. There will be at least three more before the end of term, with the scores of the 10 highest used to calculate a grade.
Lecture Assignment 5 will be distributed Friday, April 24th, and will help prepare you for the final lab and lecture exams. I am hoping to have a sixth lecture assignment and only use the grades for the best five for your final assignment grade.
Our final lecture exam is on Thursday, May 14th, from 8 to 11 AM in this room. This exam will be comprehensive and will be worth 20% of your final grade.
Final lab exam on Tuesday, May 5th and Wednesday, May 7th. This is two weeks away! Your final lab exam will also be comprehensive.
I hope everyone is paying attention to what is flowering outside! Many families that we covered earlier this term are now flowering!

Text and Other Resources:
You are responsible for the following pertinent material presented in the Judd et al. (2008) textbook:

Rosaceae, pp. 379–388

NOTE: There is a SPECIAL web page for the ROSACEAE, accessed from our Home Page.
Rosaceae is NOT in Digital Flowers.
Some of the images linked to below were taken from our recommended text, Zomlefer, W.B. (1994), Guide to Flowering Plant Families, The University of North Carolina Press, Chapel Hill

Objectives:
After studying this material you should be able to:

Know the most important diagnostic features of the family Rosaceae and its four traditionally recognized subfamilies. You will likely be asked to compare and contrast these subfamilies. You should be able to prepare line illustrations (floral L.S.'s) showing the most important features of each of these subfamilies, as well as construct a dichotomous key for their identification. For more information on how to study families, refer to Objectives for Plant Families. Diagnostic features are those distinguishing or identifying family features emphasized in lecture and lab (and treated in italics or boldface in your textbook).

Know the major clade to which the family Rosaceae belongs.

FAMILY COVERAGE
ROSACEAE (Rose Family) Classification and Phylogeny
The family Rosaceae belongs to the Rosid Clade, Fabids Subclade, Order Rosales. It is in the same order as Moraceae (Ficus), Cannabaceae (Cannabis) and Ulmaceae (elms). For our purpose, just know that the Rosaceae is a member of the Rosid Clade.
The order Rosales is monophyletic primarily on the basis of molecular data. The order is quite heterogeneous morphologically, but does have some morphological synapomorphies such as a reduction (or lack) of endosperm and the presence of a hypanthium. (The family Moraceae is derived within the Rosales and the hypanthium has been lost; its flowers are also very much reduced.) The Rosales contain 9 families and about 6300 species.

Class Notes: Rosaceae
Rosaceae flowers are unspecialized, actinomorphic, and with flat or shallowly cup-shaped corollas. The petals have wavy margins. The flowers are adapted primarily for generalist pollinators. Considerable variation exists with regard to their fruits and in fruit dispersal. The showy flowers are variable (hypanthium shape, ovary position, carpel number), the stamens often numerous, and are never really red or blue. The family is very important for its many familiar edible fruits and ornamentals. Several genera are taxonomically complex because of hybridization, polyploidy and/or agamospermy.
..
Left and Middle: Flat, actinomorphic flowers, with many stamens and petals with wavy margins. Right: The "Rose Family" Bowl.

Class Notes: Four Subfamilies of Rosaceae
Traditionally, four subfamilies recognized based on fruit type, carpel number and fusion, ovary position and base chromosome number.
Based on results of molecular systematic studies, Spiraeoideae is expanded to include the classical Amygdaloideae and Maloideae (and a few Rosoideae), the Rosoideae are defined more narrowly, and the Dryadoideae subfamily (4 small genera from classical Rosoideae) is now recognized (see Table 9.3 in your text for diagnostic features of these three recently circumscribed subfamilies). For our purpose, and for consistency with Digital Flowers and your Class Notes, we will continue to recognize the family as comprising four subfamilies and characterize them as they are known traditionally. You are also not responsible for the tribal-level classifications discussed in the text.

Four Traditional Subfamilies in Rosaceae (with their base chromosome numbers):

Spiraeoideae (spirea subfamily), x=9
Rosoideae (rose subfamily), x=7
Amygdaloideae (peach subfamily), x=8
Maloideae (apple subfamily), x=17

Base chromosome number = The inferred ancestral haploid chromosome number of a taxon
Cladogram of Rosaceae
Another cladogram of Rosaceae. Note, the Actinorhizal clade in this cladogram represents the subfamily Dryadoideae. Its four genera are unique in the family in that they all fix nitrogen through a symbiosis with the actinomycete Frankia.

ROSACEAE SUBFAMILY SPIRAEOIDEAE

Class Notes: Spiraeoideae
Drawing of Spiraeoideae
Photo of Exochorda flower in longitudinal section, representing the flower structure of subfamily Spiraeoideae
Aruncus, Fig. 9.74 in Judd et al., Rosaceae subfamily Spiraeoideae
..
Left: Spiraea x vanhouttei. Middle: Short hypanthium, apocarpous gynoecium (5 distinct carpels), superior ovaries. Right: Each carpel will mature into a follicle.

ROSACEAE SUBFAMILY ROSOIDEAE

Class Notes: Rosoideae
Drawing of Rosoideae
Photo of Rosa flower in longitudinal section
Photo of Fragaria flower in longitudinal section
Rosa, Fig. 9.75 in Judd et al., Rosaceae subfamily Rosoideae
..
Left: Flat petals of Rosa. Middle: Deep hypanthium, apocarpous gynoecium (many distinct carpels), superior ovaries. Right: a rose hip, formed by the fleshy hypanthium enclosing many achenes.

ROSACEAE SUBFAMILY AMYGDALOIDEAE

Class Notes: Amygdaloideae
Drawing of Amydgaloideae
Photo of flower of Prunus flower in longitudinal section
Prunus, Fig. 9.76 in Judd et al., Rosaceae subfamily Spiraeoideae tribe Amydgaleae (the former subfamily Amygdaloideae)
..
Left: Rounded petals of Prunus padus with wavy margins. Middle: Large hypanthium, monocarpous gynoecium with superior ovary, and numerous stamens. Right: A beautiful ornamental tree from the genus Prunus.

ROSACEAE SUBFAMILY MALOIDEAE

Class Notes: Maloideae
Photo of Malus flower in longitudinal section
Drawing of Maloideae
Amelanchier, Fig. 9.77 in Judd et al., Rosaceae subfamily Spiraeoideae tribe Pyreae (the former subfamily Maloideae)
The origin of the maloid group (x=17) from some ancient hybridization between an amygdaloid (x=8) and a spiraeoid (x=9) is falsified based on recent molecular evidence. The maloids arose from an x=9 genus, and aneuploidy could account for the base number of 17 (from 18).
..
Left: Flowers of Malus, crabapple, photo taken on campus. Middle: A hypanthium and a syncarpous gynoecium of 2-5 carpels with an inferior ovary. Right: A pome fruit, with the outer flesh developing from hypanthium tissue.

A poem by Robert Frost, called "The Rose Family," published and written in 1928:

The rose is a rose
and was always a rose;
But the theory now goes
That the apple's a rose,
And the pear is, and so's
The plum, I suppose.
You, my love, are a rose,
but were always a rose.

Here is an old botanical riddle (thought to be attributed to Albertus Magnus, 1193-1280):
On a summer's day, in sultry weather,
Five brethren were born together.
Two had beards and two had none,
And the other had but half of one.
Here is another version (from The Countryman, June 2000):
We are five brothers at the same time born,
Two of us have beards; by two no beards are worn,
While one, lest he should give his brothers pain,
Hath one side bearded and the other side plain.

Five extra points on the next assignment to the first person who sends me an email answering this riddle. Twenty extra points to the first person who sends me an image I can post that shows clearly the answer to this riddle. (Twenty-five extra points to the person who can do both!)

Rockin' Rosaceae's, Wildflowers and Plants of the Inland Northwest on You Tube!

Other resources:
Rosaceae from Wikipedia
The origin of the apple subfamily, American Journal of Botany

Click here to get home!